My universal player is dying. Upgrade suggestions?

Nope, no blue smoke... all my tubes are fine, it's always the solid state stuff that starts failing. The player refuses to send anything other than stereo signals, the front screen stays black while playing, the player refuses to acknowledge any remotes... crabby fellow, won't cooperate.

Which is better, the Denon 5910 or the NAD M-55?

The universal player just doesn't ad up at all when it comes to reliability. They all seem to fail one way or another in there ability to read shortly after purchase.

I've had a Denon 2910 for a number of years and haven't had any problems. I think you'll be hard pressed to find something significantly better for your price. The 3910 has the same video circuit and slightly better audio. The 5910 is another step up, but I don't how much. Oppo offers a great bang for the buck, but have you seen/felt its construction? It's cheap in comparison to Denon.