Originally Posted by doctormord
As the amp is most likely to amplify linear, there's no "bass enhancement" involved. Linear amplifiers are just like that, the don't color/enhance/hide/add anything, they just make it "loud".
From the years reading here in the forums, it is a common phenomenon that new amps "lack bass" at first but things start to get better when coupling caps are changed for expensive ones together with changing the input stage's opamps for some uber top-notch industrial ones like LMAsomething.
Have you tried changing polarity of one speaker to see if it's not just a phase thing?
doctormord, with all respect, there _are_ very audible differences in how various amplifiers sounds. The seems be be a hell of a lot of difference in how transients are handled, but I can't verify that. Even in amps that have seemingly equal frequency response and TDH.
Just dismissing reports of audible differences because they are not backed by hard evidence does not mean they not exists, just that they might be very hard to measure in a controlled environment. And most of us don't have the equipment and training to do such a thing.
Case in point; I have both the TPA3255EVM, a TPA3250 and a SureAA-AB32313. The EVM board and the TPA3250 lacks in bass and at first sounds a bit dull compared to the Sure, but in the end wins out by sounding more neutral. All this before any modification to the EVM (which I haven't had any time to do yet).
Apart from internal diffencencies in the boards there are the external reasons for that. It can very well be as you indicated input impedance; there's a difference between the boards. But also in how they handle the the speakers load, with it's frequency and amplitude dependent response.