[Whomper]

I also have a DM37, and I'm very pleased with it - using it to drive an old pair of Mission 760SEs. Bass is indeed superb, as is the sound quality in general.

The "Optimisation" you refer to, which seems to be switched on by default, applies an EQ that makes the system sound good through the matching Denon speakers. If you're not using them, you should turn it off ASAP - I also disliked the effect it had on the sound.

I've tinkered a bit with the USB MP3 playback, and it's not really worth it, IMHO. The playback isn't gapless, and the folder browsing only lists folders that actually have MP3s in, so you can't browse by artist, then by album, etc. Pity, or I'd have wired in an external HDD with a copy of my iTunes library on there. Not what I bought the system for though, so it doesn't bother me.

The only two major gripes I have are 1) the volume increments/decrements gained from pressing volume up/down on the remote are too large, and 2) the DAB mode feels a bit tacked on - the UI's a bit of a faff, and it forgets all your presets if you unplug it (it remembers you *have* presets, just doesn't remember what they are, and tunes you into Arrow Rock over and over again). Both DAB and FM are crystal clear though - the FM is so good, it's almost indistinguishable from DAB.