McCormack DNA 500 vs DNA 225 upgraded

One benefit of the DNA 225 over the DNA 500 is the input impedance. I owned the 500 and the 10k ohm input impedance limits your choices of tube preamps that won't result in an impedance mismatch (rolled off bass and highs). The DNA 225's input impedance is 100k ohms so it matches with a wider variety of tube preamps (output impedances). I've learned through experience and through the benefit of experienced members here.

The DNA 250 is said to run considerably hotter than the DNA 500--not sure whether that matters in your application.

I had a DNA .5 Rev A and just picked up a DNA 500 used. The same house sound is present in both of these amps. Obviously the headroom on the 500 is just over the top, giving it better dynamics and more "pop". I also really do not need my subwoofer anymore since the bottom end is just deeper and more controlled. There is also an increased soundstage depth and width and presence over the .5 Rev A, by a smidge. My tube preamp mates well with it, but the impediance is a concern for some so check into it. The 500 is also balanced, so you may get more bang for your buck if you have a balanced preamp and source to use with it.

If you like the Mccormack house sound you can't go wrong with either.

In my above post, I reference a thread which should have been titled:
"McCormack DNA-225 Platinum Edition Upgrades"
(without the word "amplifier" after it)
In that thread, the reviewer/poster states;

I would recommend a transformer-based passive or very neutral tube pre with this amp so that the full luster of the DNA-225 can be realized. In original configuration (100Kohms input impedance) the DNA-225 was a bit particular about volume control. While a high quality and finely stepped attenuator is still crucial, in my mind, it is not as much so given the new input impedance of 10Kohm.

Not quite sure what he is getting at regarding volume control, but his post implies the upgraded DNA225 may have an input impedance of only 10K ohms, which would restrict the preamps you might use to those having output impedance of less than about 500 to 1,000 ohms across their bandwidth.

Also, there used to be some posts around here from someone who had their DNA500 upgraded, although I could no longer find them. I know the DNA500 upgrades are not posted on the SMc website, but I believe there may be a few things Steve can do to improve that amp sonically, and also to provide a higher input impedance by using transformers. If that is a direction you want to go, you should check with Steve/SMc.

Thanks for the input.

Heat could be an issue as the equipment is in a cabinet. I could add in a fan if I had to.

My current preamp is actually a digital processor, an Anthem D2 with Arc room correction. I am not sure how this would match impedance wise, (I am a complete novice at this area). Steve McCormack suggested that I also add in a preamp though.

As to matching either amp for sound quality the equipment I currently have is more digital at this point
McCormack HT5 amp (5 channel)
McCormack UDP1 universal disk (Deluxe)
Anthem D2 processor with Arc
Dennon DVD 3800 Bluray
B&W Nautilus N804 fronts, HT2 ctr, SCM surrounds
HD DTV receiver
Audioquest cabeling.
etc.

Thanks for any suggestions