Any benefit from" same brand" amp/pre-amp??

The Stratos will work with the quad preamp. Output/input sensitivity is fine. What speakers will you be using?

Bass is limited by transformer and any of the indirect coupling of the output stages. It's less-likely limited by class of operation.

'd' amps may be said to have problems with hi frequencies, especially with low impedance loads...at those frequencies. The output zobel is the cause.

Look up the info on the top B&O ASP 1000 module as used by Bel Canto and many others.

http://www.icepower.bang-olufsen.com/files/solutions/icepower1000asp.pdf

It's pretty much all done at 30khz, into 4 ohms.

LF problems? Tell that to literally dozens of Sub Makers!

To UNSOUND: I am not sure why the TAS reviewer made that claim: (see TAS issue 203--July August 2010); I am not as techically hip to challenge the claim and also may have misinterpreted his statement..... However, there is an internet audio dealer who offers 2 separate levels of upgrade to the Quad 909 amp which is said to improve the bass; but the upgraded versions are not inexpensive---there is approx a $300 upcharge to go to level 2; I think Quad would probably invalidate the warranty of "new" pieces that were modified. For the record, I have a pair of Acoustic Zen Adagios. Thanks Jim

Sunnjim, perhaps it's something peculiar to that Quad amp. Most seem to feel that with the right speakers, that bass response is a strong suit of some Class D amps.