Problem is, at certain point most amps just don't sound bright or warm any more and should sound neutral when matched with speakers that are designed to be driven by most competent amps. There are always exceptions and there are amps designed to sound warm.
Let's start calling a spade a spade, well made preamps and amps like those made by Anthem, Bryston, Krell, Musical Fidelit, Marantz, Parasound, Passlabs, McIntosh, even Bel Canto, are going to sound similar to the point it is hard to pick one out when listened in blindfold. Obviously the list could go on but I just want to list Brands I have at least listened to. In my opinion (not necessarily facts but could be), those who reported night and day difference amongs such amps are either exagerrating to make a point, not volume matching or did somethin wrong in their setups, Placebo prone, or a combination of those things.
I have done my share of trying to find the best combination of components I can afford and am getting tired as my efforts always ended in realizing to get the best sound quality reference to unamplified sound I heard in live concerts, I must only listen to media, digital or analog that give me that kind of sound quality. Beyond that, it is the speakers that determine sound quality in my room. REQ such as XT32 works for me too as it does a great job with bass management, saving me hours of trial and error.
One last thing I am trying to find out once and for all, is whether the highly regarded Oppo 105, with the flag ship ESS chip makes any difference when compared to the entry level ESS chip equipped USB DAC I have and a flag ship Burr Brown/TI DAC chip equipped portable player that I am on order. Early indication is that the answer would be no, but I need more time. Regardless of that outcome I will still acquire a HA-1, obviously for reasons other than sound quality.
For the OP, I admire his patience evidenced in his multiple threads. I really think he should stick with his Marantz Integrated amp, even if that means buying a second one of the same, new or used. Or just pull the trigger on one of those warm sounding pre/power or integrated amps by design. Other than that, a sub with integrated REQ should also help him greatly, but that's just my guess.
