[bassophile]

Go with money no object for kicks, but at the same time, if you can, suggest a reasonably priced alternative as well (say about £250)?
 
EDIT: and also, is the source more important than the amp for bringing out deep bass?

 

[AlfBaxter]

I can recommend the Matrix M-Stage. I use it with HD650, and the lows are very detailed and prominent. The overall sound is warm, smooth and a real pleasure to listen to. Could be a bit more punchy, and if anything the bass is a little strong for my liking, but that's probably the HD650. If it's deep you want, the M-Stage/HD650 combo won't disappoint.

 

[gsevilla]

I have the Matrix M-Stage with HD650. Make sure you feed the M-Stage with a DAC. I tried it without my Centrance Dacport and the bass was not as deep or present and there wasn't as much richness to the sound. I'm very happy with my M-Stage, Dacport, HD650 combo. I can listen for hours with no fatigue and the sound really takes me away.

 

[Uncle Erik]

No, the source has nothing to do with it other than the recording coming through it. Source differences are usually overstated here - the primary difference with digital sources is output power. Some have more, some have less. People mistake that for "quality," when most digital sources sound frighteningly similar when level matched. Analog, on the other hand, changes a lot when you're talking about turntables. But that's another thread.

Anyhow, you should probably look at a M^3 built with the variable bass control. It's a sweet little design and the M^3 is an excellent amp. It should fit your budget and you'll be able to adjust the bass to your liking. If you really want to go cost-no-option, have a balanced M^3 built.