Home > Consumer Reviews > iriver SlimX iMP-550 CD / MP3 Player with Ultraslim Design

My first MP3 CD player was a Sonicblue Rio SP-250. It was an excellent MP3 CD player until it broke. I bought a cheaper MP3 CD player, and it was quite sub-par. This is my return to the high-end MP3 CD Players. First off, this player is the best I've used. And while it exceeds my expectations, there are still a few tiny, minute flaws.

The Good
The sound quality is superb.
The navigation is clear and easy to use.
The remote is easy to use, and has a vibrant display and backlight.
The accessories that the unit comes with are great.
The unit itself is THIN!
Battery life of the rechargable stick batteries is good.

The Bad
No controls or display on the unit itself.
Radio reception is not quite perfect (I find my self shifting the remote around to try and get better reception. To my surprise, it works).

Conclusion
In the end, I'm very pleased with this player. It is, in my opinion, the best MP3 CD Player on the market. Everything is done great, with minor flaws. The benefits far outweigh the problems with this CD player. However, if you MUST have perfect radio reception wherever you are, or you don't like having to work the player through a remote, this player might not be good for you. For the rest of us, who are just looking for a good MP3 CD player that has the versatility and quality not found in most other players, this is the Holy Grail of CD players.

This cd player has all the features I was looking for and more that are a total bonus. It plays MP3's, WMF's and regular cd's. I don't use the headphones that came with it because I have a very nice set of Sony studio type phones. The combination of the player and my phones is incredible sounding. I love the remote control. It makes it so much easier to control when you are in bed or in the car or have it on your belt, etc. You don't have to take the player out of its protective holder to get at any of the controls, only to change the disks. The equalizer is worth the price by itself. It has some presets, but you can totally control about 5 different levels, plus right and left. The remote even displays the name of the disk and song if your cd has that kind of information tag on it. I also love the fact that the firmware in the player is upgradable online. It's a very easy operation that almost takes care of itself. I upgraded right away from firmware ver. 1.03 to 1.10. The player itself is beautiful. The case is black and silver metal and comes with a velvety protective case that will slip onto your belt. I don't mind paying a bit more for this kind of quality. This is a great way for an adult to treat themselves to a new toy.

It's expensive. That's because it's the best. Here's why:

Functionality: It has every function you could want and some you never thought of, up to and including a mode that makes the mechanism quieter, so it doesn't bother the people around you. Plays audio CDs, MP3 and WMA, with upgradeable firmware for future formats. Excellent navigation lets you scroll through the list of songs without interrupting the song you're listening to. Supports ID tags and CD text (so you see track names for regular CDs too). Very good memory buffer for shock protection (caches the entire MP3 file, or up to 320 seconds of audio CD, and reads ahead to the next MP3 file so there's no wait between tracks). Equalizer presets and customizable settings.

Sound quality: Rivals my Yamaha 565 home deck. It's the best sounding portable I've tested. In addition to headphones out, it has line out and digital out to plug into your receiver.

It's small: Looking at it from the top, it's barely larger than a CD. From the side it's 0.54 inches thick. If you have a spindle of CDRs handy, stack 9 of them on your desk - that's how large it is.

It looks damn cool: Simple black and silver design will look good in your backpack of with your business suit. Comes with a padded sleeve you can keep it in that doesn't interfere with operation. All controls are on a small remote with a clip on the back. Also includes a car kit - remember when you had to pay extra for that?

The included "headphones" are, of course, crap. Pair it with the Sennheiser PX100 for portability and value or the Sony V700DJ for style and sound quality, and you have the best portable rig, period.

I went and purchased an imp-550 and an imp-450 and got the chance to get to the bottom of the imp 450 and 550 sonic differences in relation to my trusty imp-350.

First off, no disrespect to the imp-350; it's no slouch; it's sound quality is great, basically bombproof and the user EQ has plenty of bass boost. At times, however, with older tracks that need that little extra boost the 350 didn't quite cut it--it's only shortfall, and a slight one at that.

So, out of curiosity, I stepped into an imp-550 Initially, it was great because of the small size, but it FEELS delicate and reports of quirky behaviors and bugs (of which some I did experience) stopped me short. Plus there are sonic oddities which I will now address.

Sonically, with a flat EQ, the 350/400, 450, and 550 are all about equal in terms of warmth detail and clarity. The only bonus out the the bunch is the imp-550's optical line out. I did not test it, but have read twice that it was decent---but nothing special. Where there are huge differences, and to me make or break two of the players, is with the EQ settings. (For the record the imp-350 and imp-400 are identical sonically in every way, with the 400 being a cosmetic change and that's it.)

Before I proceed, yes, the imp line and possibly the iRiver line in general is not sonically as pure as some other media players (HDD's and vintage CDP's included), it is however, probably the most "fun" sounding line up of media players which can add amazing bass boosts and other sonic tweaks to stimulate the user...in small well designed packages.

Back to the imp-550. It features an Extreme 3D (a stereo imaging DSP processor that creates a virtual surround effect) and Extreme EQ. The 550 has the familiar iRiver EQ presets like Rock, Jazz, Metal, Blue-grass, uBass, etc, but instead of user1/2/3 EQ it utilizes the Extreme EQ feature. ExtremeEQ is a 5 band EQ adjustable both db+ and db-. The presets on the 550 are amazing. They color the sound greatly and very cleanly. The problem with the imp-550 sonically, is that when adjusting the sound with the Extreme EQ you can not achieve the levels of sonic adjustment that the presets offer. The presets are indeed good, but in my case I just want to boost the bass, like the rock preset, but without the added treble. I tried this with the Extreme EQ, but with the bass boosted to max it makes hardly a difference. iRiver has yet to address or rectify this problem with multiple firmware updates. I grew frustrated that with the imp-550 the bass was great but too treblely or the bass was not enough. Coupled with the nagging other bugs and quirks with firmware, and the 550 does not offer a worthwhile change from the imp-350/400.

From this point I contacted iRiver to find out the differences between the imp-550 and new imp-450, and was told that they share very similar components (including processor chips) and the the imp-550 is discontinued in the USA. Further, the imp-450 is its replacement, and as demand for a high-end mp3cd player is declining in the US, the upcoming imp-900 is not for the American market either.

So, my thoughts started to wonder about the imp-450. Upon further research which included downloading and thoroughly going through each players respective .pdf manual I discovered the the 450 and 550 are very similar players indeed with one notable sonic difference. there is no Extreme 3d/EQ in the imp-450. I began to theorize that perhaps the 450 could possibly remedy the 550's EQ bugs decided to try to dig in the forums to find out. To my surprise there wasn't much info out there. I did read in the imp-450 manual though that it had an EQ much like that of the imp-350/400, presets and 3 user EQ's. The major difference is that unlike the 12db bass boost on the 350 the 450 had a 18db boost. My suspicions were beginning to take shape.

Today my imp-450 arrived. It is a beauty. Considering I had a brand new imp-550 last week, I can say the 450, is esthetically more pleasing and much better built than the imp-550. For example, the lid does not feel loose or shift side to side slightly when closed. It is definitely smaller than the imp-350 and of course identical to the redesigned 350, the imp-400. Its weight feels about the same as the 350 and only slightly heavier than the imp-550. Overall the size differences between the 450 and 550 are slight at best. Hands down the imp-450 is the better more secure feeling and esthetically pleasing player. (note: the iRiver pics do not do this player justice at all....it REALLY looks nice and is QUITE small)

At this point, I would like to add that the presets on the imp-350/400, even without comparing them to the 450/550, offer very subtle change in sonic characteristic and one really must use the custom user EQ's to get sound to really maximize its potential.

Yes, and after much discussion, I can report that the preset EQs on the 450 and 550 are identical! They both offer amazing sound boost. Furthermore, the user EQ's DO offer 18db of adjustment, however the control on the remote offers the adjustment in steps of 2db (0,2,4,6,8,10,12,14,16,18). The treble is only a 6db adjustment as in 2db steps. I can also confirm that the user EQ's sonic adjustment equal that of the presets and it not deficient like the user EQ (Extreme EQ) on the imp-550.

Next I performed the following test.

imp-350 user EQ bass set to 12db, treble set to 0
imp-450 user EQ bass set to 12db, treble set to 0

The two units were identical in sound. Next, I boosted the imp-450 to a full 18db and, yes there was a substantial increase. Clear, clean, detailed, tight bass sprang from this little player. Its has all the bass boost of the recent firmwared imp-550, but with the user EQ control of the imp-350!!

I personally not only feel validated, but that I have reached my sonic nirvana. I was very pleasantly surprised, as I was expecting the imp-450 to fall short and have the similar problems of the imp-550.

So, in conclusion, the imp-450 is the definite winner here, and at a bargain price. I cannot see any reason one would choose an imp-550 over a 450. Physically and sonically superior, the imp-450 easily beats it. Im only slightly curious about the imp-900 now, as I cannot possibly see how it could be better, except for battery life. But since it shares the same micro 13.7mm size as the imp-550 I wonder how the build quality is.

My personal opinion, after owning all the major imp players, is that the imp-550 was a great concept that just didn't pan out. Not only that but I think that challenges of utilizing the Extreme3Q/EQ efficiently has been questionable as well. I think they countered the shortcomings and struggles of the imp-550 with a slam dunk of a release with the new improved and dare I say, perfect, imp-450.


*EDIT/UPDATE: Well, I must correct myself as I proceeded to do some further imp-350 and 450 tests. I ran a selected mp3 track in both players side by side with the EQ set flat on both, volume set to 30.
The headphones I tested were both a well broken in Sennheiser px200 as well as Sennheiser HD 25-1, also well burned-in.

The two players do indeed sound different, noticeably so. The 450 is defintely more punchy sounding and a bit more dynamic, open and involving, while the imp-350 sounds a bit thin, and slightly small sounding in comparison.

I am not a golden eared individual by any means, but I was easily able to tell a difference between the two.

Sorry to give the earlier impression that the various imp's are sonically similar. i can honestly say now that the later models do step it up a bit in the sound department. But hands down the imp-450 with its unflawed performance and quality wins, even without the added features of a optical line out, slightly larger size, and inability to charge whilst playing. Cool features of the imp-550, but not needed.

Having already owned an IMP-350 I knew what to expect from Iriver when the 550 came out. I passed on buying the IMP-400 because other than appearance, the Imp-400 and 350 were pretty much the same. The thing about Iriver's IMP line is that they are not your average cd players. These cd players are in class all their own offering features that no other brand on the market can come close too. The IMP-550 is the latest " advanced cd player " to enter the market and this time they have made this player different enouph to give consumers who already have the 350 or 400 a reason to upgrade. First is the players size. Even though the 350 was slim, the width and iregular shape more than made up for this and it was akward to carry around. The 400 was not really all that smaller. The 550 finally delivers in making a compact player and while it is not as small as the Sony D-EJ2000 it should prove portable enough to carry around and even exercise with. The next thing is the sound quality which quite simply, is superb. There have been instances when while listening to certain cd's that I can pick out sound characteristics that I did not notice before. The 550 also has two new sound features Extreme EQ and Extreme 3D. Extreme EQ is simply the user defined setting only you set it by adjusting a 5 band sound control panel. Ths gives the user more control over the EQ than in the earlier models. Extreme 3D is a DSP setting ( digital signal processing ) that is supposed to mimic surround sound. While the Extreme EQ is a very nice touch, the jury is still out on the extreme 3D I have found that sometimes it works well for some music and not so well for others. the forum board has a lot more by the way of user comments. Neither sound feature is available for the 350 because it does not have the proccesor chip set that can support this. I have also heard that the same is true for the 400 as well. and finally this player has a few things that the 350 and 400 don't have such as the ability to charge and discharge the batteries while listening to it. a etiquette function that reduces the mechanical noise the player generates and a car kit that comes with the player to name a few. This player has excellent anti-skip protect as well. My friend went jogging with this player while the ESP was set to 80 seconds and it did not skip once. there are some minor gripes I have though such as, the fact that like it's predecessors the 550 eats through the batteries. the player also has no buttons at all on the unit. the player is completely dependent on the remote to control it. and there is a headphone adapter that you need to use because the headphone input on the remote cannot fit most headphone jacks ( too sunken in ) All in all a great cd player with few problems.