I will also chime in and tell you that DT150s are definitely NOT mere "midrange" 'phones. They pretty much trounce the DT770 (which is much-hyped here on HeadFi) in all areas except perhaps bass impact (DT150 bass tighter and more detailed though), and are priced similarly. I'm not sure why so few here on HeadFi have experience with them (somewhat harder to find than DT770, but readily available through several well-known retailers-mine came from BH Photo). I have compared them with several considerably more expensive cans, and nothing I have encountered thus far does a better overall job of accurately communicating the source material. Some of the higher-priced 'phones may do certain things better than the DT150, but IME this consistently is at the expense of other performance parameters. Also, the DT150 build quality is far, far ahead of most of the high-end cans (even though it IS pretty ugl..,er,"industrial" in appearance-looks like it belongs in a speech therapy lab!), and every part is replacable (and Beyer customer service is excellent).
As to source/amplification components, I have found these 'phones do best with amps which can supply plenty of current. I have used ASL MG-Head OTL Ver. III (pure tube), Musical Fidelity XCanV3 (tube gain stage, MosFET outputs), and PS Audio GCHA (pure solid-state). The ASL made for a very pleasant sounding system (warm, "musical", and nonfatiguing), but was simply too laid-back and lacking in details-consistently found myself turning up the volume to try to flesh out more detail, and occasionally nodded off to sleep (this setup DOES help alleviate some listenter/ear fatigue due to poor recording quality). The GCHA made for a very lively, detailed sound (which is what I prefer) but lacked the warm, "comforting" sound of the ASL. I found (to my ears) the best of both worlds in the XCan V3 (NOS Russian 6h23-EB tubes); I bought this amp when priced US $399-it now retails for US $499, which is still a good value given the level of performance (build quality is also very nice).
As to source components, get the best you can afford. The DT150 will EASILY reveal the differences in sources. My best digital source components are the NAD C542 CDP, Bel Canto DAC-2, and Metronome Technologie CD-2V (Signature); I can EASILY discern the improvements as I move up the chain, starting with the C542 alone, then C542-->DAC-2, then CD2V (all using XCan for amplification, which is also very revealing of differences in sources). The CD2V is not the end-all, be-all of CD players but IS a legitimate "high-end" design which is perfectly competitive with other players (actually better in many regards, which is why I own it
) in its price range ($3500 when I bought in 2003, would now probably cost $5000 given the weak US dollar); the point is that the DT150 is definitely a 'phone that will "grow" with you as you upgrade your sources.
If I were in your position, I would probably spend my current budget obtaining a good amp (X-Can V3 is the winner out of the ones I have used) and would then save for a source upgrade. The DT150+X-Can is an excellent foundation which will respond beautifully to source upgrades at least through the "mainstream" high-end price range of US $3000-5000. Equipment costing more than this price range is deep into the "point of diminishing returns" territory where spending more money only yields minimal improvements.
Anytime I give anyone advice regarding equipment, I also encourage them to save enough to buy some new recordings for their collection. I would give you the same encouragement, but the fact is you are going to have so much fun hearing new things in recordings you already own that you may not feel the need to acquire anything new for some time.
I hope this helps. Congratulations: from your post it appears this is your first foray into the world of high-end 'phone listenting, and you are off to a GREAT start with the DT150! You are going to experience first-hand just how much great music can enhance your quality of life in all areas.
Sorry about your wallet though!
