Looking For Single Source Tube Preamp

Well, I don't know . . . . . . You have a very nice system and an intelligent way of configuring it. I don't think your (occasional?) problem is a "tube vs. no-tube" thing, otherwise it wouldn't be occasional, it would be all the time.

I'd look elsewhere. Cabling?, you didn't mention. Or probably more likely the source (the Denon). If I had your system, the first thing I'd be looking to upgrade (unless it turns out you have really crap cabling, which I doubt) would be the CDP.

If you are as you seem to imply, a single source digital guy (a perfectly valid approach, though not mine) you really owe it to yourself and your ears to work your way up to the finest you can afford in that department.

Going to tubes at this point represents a radical departure for you, and won't do anything to clear up the problems of harsh digital playback. I've nothing against Denon BTW, but your hearing is obviously getting more refined, and you can now enjoy the benefits of better digital playback equipment. Even an older Wadia or Levinson setup will IMO beat the pants off the modified Denon.

And one more thing: if you want to mess around with tubes a little, again, do it at the source -- ie a Cary CDP, etc.

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I'm not familiar with your preamp or your speakers, but I've been running M200 Sonatas in many many different system configs - never any harshness. This includes using a Denon 2200 multi player as a source.

I think Nsgarch has given the best advice, but if you just want to experiment, the Dared 2000A is a 2 input tube preamp with remote volume. They show up on A'gon now and then for $300+ used with upgraded tubes, and I think can be bought directly for under $500 (or 450)

I have one and it's pretty nice for the $, and combines nicely with the M200s

If your Denon is the APL mod, then I doubt it is the problem. I have a very revealing system and there is no trace of hardness.

http://www.space-tech-lab.com/Products.html

Space tech has great sound, excellent quality and reasonable pricing.

Space Tech Labs can build you a single input tube preamp at a very reasonable price. They sell multi-input models, but Albert will pretty much do what you want.