McCormack DNA 500 vs DNA 225 upgraded

I have heard pretty much the same thing Cmach posts above from Steve McCormack. However, your question is pretty much answered in posts made by Steve in a thread titled;

"McCormack DNA500 and DNA2"

You might also want to check out a thread titled;

"McCormack DNA-225 Platinum Edition Upgrades Amplifier"

The used prices of DNA 500's right now are hard to beat. The DNA 500 is a very nice amp, although IMO not quite to the level presented in the IAR review. I would only go to a modded 225 if I was going to get the top platinum mod and have them converted to monoblocks. The first pair I have seen posted for sale here was only about a month or so ago.

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.

I believe Steve is partially/mostly (trying to be) retired, like others of us, so you may not hear from him.  He has not had anything to do with the DNA 500 or 225 for many years as Conrad Johnson acquired McCormack Audio and took over those designs.  Steve’s company SMc Audio performed upgrades to both but maybe not the DNA 500 any more.

I will not try and answer your questions but as a former owner of the DNA 500 I can say it is effortlessly driven by virtually any solid state preamp, and that I have successfully used it with tubed preamps with output impedance as high as 600 ohms.  The old rule was a minimum of 1 to 10, output impedance of the source to input impedance of the load.  My personal goal was to keep that ratio at 1:20 or better.

Here are some specs for the DNA 500, FYI:

 

• Output Power:
  • 500 watts per channel RMS into 8 ohms
  • 900 watts per channel into 4 ohms
• Output Current: 50 Amps peak per channel
• Input Impedance: 100k ohms
• Input Sensitivity: 1.2V
• Frequency Response -3dB at 0.5Hz and 250kHz
• Rise Time: ±2µs
• Slew Rate: 50V/µs
• S/N Ratio: 88dB, "A" weighted
• Damping Factor: >100 (1kHz, 8 ohm load)

Different designs. The DNA 500 and 750 are bridged designs while I believe the 225 is a stereo amp.