I'm more of a believer in burn-in on components with moving parts, such as speakers or even CD players. But, I think there is also a break-in process for amplifiers (and integrateds). Anything that energy moves through and is altered in prone to changing over usage time (think capacitors).
I like to think of the metal halide lighting system over my reef aquarium. It's a component that uses energy (a lot of, based on my hydro meter), is electronic (the ballast), and goes through a break in period with every on/off cycle... the ballast kicks in, warms up, cycles to peak, ignites the vapours in the the bulb, and the intensity and colour temperature changes during the on cycle.
It also generates crap-loads of heat, but that's besides the point.
I think it would be more of an issue with tube-based amplifiers than SST. However, other SST components (not necessarily audio) often have a factory burn-in period specified, but that may be more related to verifying the absence of any fauty components than to optimizing performance.
Whether or not there really is a burn in period or not, if you've been running your amp for a week or two worth of hours, you can consider it done.
Some speakers change a good bit in their initial use. Typically the cone's losening up on the speakers after being flex'ed for a while.
The next thing that most folks talk about is capacitors taking some time to reach a steady state condition and di-electrics on cables getting polarized to the signals running through them. Again a few weeks would cover this.
Still some controversy about whether there really is burn-in or whether it's more your brain burning in to what your new equipment or your credit card is doing. I'd tend to go with the ears more than the brains. But the differences are generally subtle and tend to be hard to detect unless you've got some way to compare the current and the before case. And even then - it's subtle and subject to debate. There are some that would suggest you leave your amp and pre-amp powered on all the time for such reasons - probably more applicable to tube amps than SS, but even for SS some would say it's a good idea as in it might take a few hours for your amp to settle out after powering up - but this might be more for either very high end equipment that is capable of resolving such things or prehaps some rather esoteric amplifiers designs.
If something goes from sounding bad to sounding good - that's pretty dramatic and mostly unusual in something like an amp.
A friend had a NAD receiver that changed its sound in the first 2 weeks...then it died. Not a knock on NAD at all, just thats what it happened to be.
I dont think it bodes well for an amp to change its sound. It seems that the designer and factory would be unable to control things so well if the thing requires something more than they are able to provide. Maybe thats left-field thinking?
Bryston has a factory burn in on all amps, but I think this is more of a function of making sure the amp is going to outlast it's 20 year warranty than a change of sound.
You are right, I do have more bass. I left the tone controls alone and actually engaged the tone defeat button. I've been so used to listening with a lot of bass and treble that I'm getting used to a flat sound.
I need to learn more about placement. Since my system involves a PC I listen mostly nearfield. I assume you mean speaker distance from the listener and from each speaker. My wife bought me a leather chair for my office so if I'm not on the PC and I will be sitting about 6-8 feet from the speakers. I may have to adjust the angle of the speakers.
I think my next upgrade to support the new Evo's will be the Rega Mira. Of course, I don't plan on doing this anytime soon but at least I know that I can a get a used one for around $700 which is much less than I expected. I'm also considering purchasing a higher end CD player.
No, the DAC is working great. Again, this is the first time I've purchased a DAC so I really have nothing to reference when it comes to the sound they produce. I'm sure this could become the weak link and I will need to upgrade to a better DAC. For now though it does what I need and for $110. The reviews have been excellent. I need to have 3-4 DAC's to compare to understand the differences in sound quality.
Why do you ask?
Several knowledgable people on this board recommended that I may want to move into a better integrated to really maximze the sound quality of the Evo's. The guy at STO that I bought the speaker's from recommended the Brio as option but really thought the Mira would be best. I know Creek makes and excellent IA too. I'm mainly just doing some advance thinking about upgrades and the cost. I will probably try to find some shops around town that I can go and listen to different equipment before I shell out anymore money. I think the NAD 325 and the Evo's will more than meet my expectations. I'm usually fairly conservative when it comes to spending large amounts of money ($500 and up) so the Mira would require some real critical thinking. I also feel like I have to use the equipment enough to justify the investment.
On speaker placement, you typically would want to put the listener at one corner of an equilateral triangle with the speakers in the other corners. Most speakers would also be turned inward slightly so that they aim at a point a little behind the listener, with line of sight passing by the nearer ear. The triangle doesn't have to be exactly equilateral, but the distance from each speaker to the listener should be the same. The idea is to give them enough room so you have good stereo imaging and sound stage.
Speakers also relate to the walls of the room - the closer they are to the wall behind them the more bass you will get, away from the wall, less bass. Also more bass as they move into a corner of a room. A few feet from the real wall and side wall is generally enough to prevent getting an undesirable amount of coupling - though you can exploit this a bit to taste. The appropriate distances may vary with the size (e.g. bass response) of the speaker and whether it is ported to the rear or not - many speaker vendors will suggest appropriate minimum distances.
Vendors that do factory burn-in on parts often are trying to weed out 'infant mortalities' in the field. This kind of factory burn in would typically be long enough to get rid of any 'transient' behavior related to parts reaching some sort of steady state behavior relative to their sound characteristics.
A friend had a NAD receiver that changed its sound in the first 2 weeks...then it died.