I can't imagine the amp is the root of your problem (ie lack of warmth/musicality). You're not likely to find an amplifier that's warmer than the B&K M200 without spending ~$1000+, and even at that price SS amps aren't likely to bring more warmth and musicality (at least I haven't found one). Tubes may be the way for you to go.
As for repairing your dead amp, have you checked all of the Fuses? I would check all of the fuses first. This includes the rail fuses inside the amp. You'll likely need to remove the driver board to check them, so if you're not comfortable with this, you can send it back to B&K or take it to a tech. Don't just visually check them, use a continuity checker. If it's just fuses, or something simple it will probably cost you $100 plus shipping (they'll do a complete checkup and bias for you while it's there). If your problem is with the output mosfets B&K probably won't be able to repair it - I don't think they're available anymore. I think the latter diagnosis will cost you ~50 plus shipping.
I think it's a coin toss as to whether you should repair or sell as is, and replace them. IMO it's worth repairing, but if I was interested in upgrading anyway, I would sell the M200s as is, and buy new amps.
One last thought - have you evaluated your room? Maybe room acoustics are to blame, at least partially.
As for repairing your dead amp, have you checked all of the Fuses? I would check all of the fuses first. This includes the rail fuses inside the amp. You'll likely need to remove the driver board to check them, so if you're not comfortable with this, you can send it back to B&K or take it to a tech. Don't just visually check them, use a continuity checker. If it's just fuses, or something simple it will probably cost you $100 plus shipping (they'll do a complete checkup and bias for you while it's there). If your problem is with the output mosfets B&K probably won't be able to repair it - I don't think they're available anymore. I think the latter diagnosis will cost you ~50 plus shipping.
I think it's a coin toss as to whether you should repair or sell as is, and replace them. IMO it's worth repairing, but if I was interested in upgrading anyway, I would sell the M200s as is, and buy new amps.
One last thought - have you evaluated your room? Maybe room acoustics are to blame, at least partially.