Glad we agree, Al. The comparison to tubes is right on, as the best of tubes - especially OTLs - that I have heard do treble so well, and it's in fact intoxicating. From my perspective the reality is, without saying too much right now, that the 500s have the treble clarity and completeness of these OTLs I've heard in the past (the name of which escapes me; it's been years); but I can't be too sure until I get my new panels in place. However, to get to this point, as I have posted under my system thread and as you just said, I had to a) go noise-hunting all around, to smooth out the treble among other things; b) find my DAC's best volume setting and further shield its output section. Details, but the amps ain't the perceived problem. Regarding the pairing with the SDR-4000SV that awsmone alluded to, I will go as far as to say this is pure analog, albeit not of the ultimate dynamic extension as other DACs/payers. I believe I said the same thing elsewhere, and the sonic qualities really come through with great tube recordings, like those by Chesky. Having said all this, I do also agree that every system has issues, and perhaps serious issues.