Advice on Krell amplifier

There are three basic limitations implicit with all high-end class A power amps, so be certain that you're prepared to cope with the challenge that they present: (1) They're big, heavy beasts that generate a lot of heat, so the installation has to accommodate those needs. (2) Class A amps often use fans, and that noise can be intrusive unless there's enough isolation. (3) Minimizing DC offset at the amplifier output is a common problem with all solid-state class A designs. I'd prefer to see a published spec. limit on the maximum permissible DC offset. The Krell Duo 175XD on-line specs don't list any specification for that parameter, so be wary. I don't like to see any DC offset that exceeds 30mV, and 50mV would be the absolute worst case limit that I'd be willing to tolerate.

Numerous responders here are Krell amp. owners, so lets ask them to chime in…
Hey Krell guys, what DC offset do you read on your power amps? Simply read the DC voltage present at your amplifier's output terminals under a NO SIGNAL condition. (Use a DC multimeter capable of reading down to the 10mVdc or lower range. Place probes across amp output terminals or across load input terminals, whichever is easier. Be certain that you are on Vdc scale, not Vac.) Advise us of your measurement. And does your reading vary much when amp is cold versus right after a heavy listening session?

This DC offset is what your woofer will normally see in use, and it will cause the woofer to be offset from its optimal centered position by that voltage. (It's only the woofer that will see any offset because the crossover network capacitors in series with tweeters will block any such DC bias.)

fast—Yes, the Krell info that you pointed me to is very pertinent; thanks.  And the DC servo correction that they cite should prove of material benefit in minimizing DC offset drift. As a consequence, I still don't comprehend why Krell doesn't publish a true spec limit for maximum DC offset, but I guess that's a separate issue. Regardless, I'd suggest making periodic measurements of DC offset to assure that it's within an acceptable margin during the first few weeks of operation. Measured results, when properly administered, provide the best evidence.

georgehifi—Yes, true. Most preamps (and signal sources) couple to the power amplifier's high impedance input through a coupling capacitor, thus blocking any DC input, but exceptions do exist. So if you don't know what your own setup does, then do assure a "no signal" test condition by selecting a shorted input.
Re. the 10-20mVdc range that you cite for acceptable DC offset…Yes, that's a tolerable offset range for a class A/B amplifier, but lots of class A power amplifiers typically exhibit greater DC offset. For example, the published spec limit for DC offset on many Pass power amps is 50mV, a value that I feel is marginal, at best. (But I applaud the fact that it's published! Of course, many buyers never read that deep.)