I currently own a DNA-1 with Revision A mods. It replaced my DNA-125, the rest of my system remained constant during the transition, UDP-1 Deluxe, MAP-1 and Harbeth M30s. So I can provide some perspective on the two units (although I wish I had compared to the DNA-225).
The DNA-125 is an excellent power amp at a given price point. A unit can be picked up for $950-1100 used on A-gon. My only slight criticism, it was a little on the "cool" side in terms of the music presentation. The DNA-1 Rev. is considerably different. Firstly, a lot warmer, bigger sound stage and better lower end & definition. The warmer sound was a good mate with my neutral & revealing Harbeths. Also, I was very much surprised (in a pleasant sense) when comparing the two power amps. I was also wrong, expecting the two units of different generations and design executions to sound a lot closer. A DNA-1 Rev A occasionally appears on A-gon, in the similar price range to a DNA-225 ($1600-1800).
Audphile1 suggested a Pass lab X250.5 - in this price range ($3500 - 3800used ), you may consider a head-to-head comparison with the DNA-500. Both are similarly priced (retail or used) and I think a more valid comparison. Once again, Steve McCormack may be in a better position to describe the sonic virtues of a fully modded DNA-225 v. the DNA-500 (I can't).
anyway, that was my experience. I hope it helps somewhat.
Good luck in your decision.
The DNA-125 is an excellent power amp at a given price point. A unit can be picked up for $950-1100 used on A-gon. My only slight criticism, it was a little on the "cool" side in terms of the music presentation. The DNA-1 Rev. is considerably different. Firstly, a lot warmer, bigger sound stage and better lower end & definition. The warmer sound was a good mate with my neutral & revealing Harbeths. Also, I was very much surprised (in a pleasant sense) when comparing the two power amps. I was also wrong, expecting the two units of different generations and design executions to sound a lot closer. A DNA-1 Rev A occasionally appears on A-gon, in the similar price range to a DNA-225 ($1600-1800).
Audphile1 suggested a Pass lab X250.5 - in this price range ($3500 - 3800used ), you may consider a head-to-head comparison with the DNA-500. Both are similarly priced (retail or used) and I think a more valid comparison. Once again, Steve McCormack may be in a better position to describe the sonic virtues of a fully modded DNA-225 v. the DNA-500 (I can't).
anyway, that was my experience. I hope it helps somewhat.
Good luck in your decision.