The307a sounded amazing, I listened to it with ps1s, hp2s and ed9s. While it sounded great with all three the hp2s sang through this amp. Normally I prefer the ps1 but out of the 307a the hp2 was the winner. This amp is clearly a top performer and should be considered by anyone purchasing a top of the line amp. Personally at 6k I would like to see a better case but my EC hd2 is not going to win a beauty contest. I am actually suprised to see this amp not steal some thunder from the b52 or rudi balanced amps.