I have no experience with the Infinitys but did recently buy a pair of the R20s, $80 for the pair at Circuit City on Black Friday.
These Polks are great if you don't have a subwoofer, or if you just want plenty of bass, esp. the boomy type---it delivers an amazing amount for its small size.
However, the R20's mids and highs are weak and muddy. Most disturbingly, they distort quickly at high volumes. At moderate levels they're okay.
I've relegated them to my bedroom, from which I took out a pair of Mordaunt Short MS05 speakers which are about 30% smaller and lighter than the Polks but blew them clear out of the water---zero distortion even with my receiver's 85 watts RMS cranked almost to max!
Infinitys that I auditioned at CC seemed to have much smoother and more refined highs, but I have no idea about how they hold up at high volumes.
I've heard the same things about the Polk R20's (which I have not listened to). It's hard to beat a decent pair of speakers for $80. The finish & build of the Polks seem to a bit off when compared to the Infinity Alpha 20's.
I happen to have both. The difference is negligable. Infinity and Polk do not make bad speakers. There are only bad room acoustics, bad speaker placement and imaging problems. In speakers, bigger is better: A bigger image means an image more like the original source. The exaggerated claims about the difference in speakers is non-sense. Polk uses laser inferometers to check their speaker cones. Infinity has delved into complex metallurgy. They both have engineers with instruments which measure well beyond the capability of the human ear. If you can't afford big speakers , buy a subwoofer, and, by all means, move your speakers around your with zeal until you find the best image for your room.I have heard medium priced speakers sound spectacular in "good" room,and horrible sound from outrageously priced speakers in a "bad" room. I am a retired acoustical engineer and I hate to give away this not so well known secret: Room acoustics;Rooom acoustics; Room acoustics !!!
My point exactly. At the extremes of high and low db's, and those existing abhorations which are near or beyond human hearing, you get what you pay for ...3 times worth? NO!! Room acoustics, room acoustics, room acoustics. Many tests have been done on the human ear, which generally cannot hear or detect anything beyond 3% harmonic distortion or any TIM at all,and which most rooms will distort to a point beyond that to the extreme.Ever listen to bass frequencies on a really good set of headphones? No speakers at any price in the average acoustical room comes close that accuracy or clarity.Think of your room as the box on really good Acoustical Guitar or Violin. No set of strings(speakers) will overpower that acoustical influence.As a designer of several dozen acoutical listening and playing chambers ,our team realized at an early stage, its the ROOM and the IMAGING.Just trying to save the average Joe a bundle of money on inaudible tripe.Its why recording studios spend so much on their chambers.
What you're saying makes sense once you have crossed over some threshhold of reasonable sound quality equipment, for example a $500 pair of bookshelf speakers probably doesn't sound a whole lot worse than a $1500 pair in the same listening space. I've owned $100 speakers before and can attest to the fact they do sound MUCH worse than the $500 ones.
However, Polk's (and Infinity's too, from what I've been told) entry level stuff like the R20 is far below that threshhold and IMO would probably sound like crap even in an acoustically perfect room. The old Biblical saw about not being able to make a silk purse out of a pig's ear comes to mind.
Consider the source! I've been recording to my computer on a refitted AR XB turntable with a Grace 707/Sumiko Oyster(the sow's ear?). Ancient Dynaco SCA-80Q and junk Philips speakers complete this super system. It sounds incredible, at least as good as my Linn heavy upstairs system. I'm replacing a blown speaker on a budget, no more than $150/pair. Junk speakers can sound great with a good source (the Linn philosophy)
Your system proves again the primacy of a quality amp/receiver, with the speakers a close second.
I didn't even know Phillips ever made speakers though...scary!
My guess is that even a cheap pair of small bookshelves in the $200 range will make a significant difference.