[MRC001]

Over 15 years ago I built my "preamp", a 10k stepped attenuator & switchbox driving Adcom 5800 and Magnepan 3.6R in a tuned listening room. For headphones, I have 2 amps: an old Headroom Maxed out Home and a Corda Jazz. Both are great, though the Jazz is just a smidge better. Driving LCD-2 (Fazor) and HD-580s.
 
Since all my sources are now digital, I'm considering replacing the "preamp" & headphone amp with a single DAC+preamp+headphone amp.
 
My current setup is neutral and revealing and I like to keep it that way. One might wonder, how can anything be better than a single metal film resistor in the signal path, which is what a stepped attenuator is? Taking the analog output of a digital source, you're already listening to the D/A converter and analog line output stage (usually opamps) in each individual device. Why not take the raw bits and send them to a single DAC?
 
Whatever I get must be usable as a preamp (analog outputs, RCA or XLR), have digital inputs and analog inputs. Something like the Oppo HA-1 or Grace M903 or Benchmark DAC1 (Pre or HDR). I've read quite a bit about these units. Any others I should consider?
Simplicity is goal #2 after sound quality (goal #1) - single box with simple function selector & volume knob.

 

[m-i-c-k-e-y]

there is the Grace Design m920

Oh I forgot for an all-in-one this is it : http://vinnierossi.com/

 

[MRC001]

All 3 of the units I mentioned will do the job - drive headphones, drive my power amp, with a high quality DAC, and at least 1 analog input (for my turntable, my only non-digital source). I'm wondering 2 things:
1. Has anyone A/B compared these with each other directly? I've read reviews and measurements of each, but nothing directly comparing them to each other.
2. Are there other units I should consider?

 

[inthere]

I have the Headroom Maxed Out Home and after 12+ years it's still sounding great! 
 
Personally I don't think you're going to really improve sound quality noticeably with any of the 3 choices. I went pretty extreme with my choices -Metric Halo ULN-8 and Prism Orpheus, (both +5000 pro interfaces when I bought them) and didn't really get the sound quality improvement I was searching for. With everything digital, if you want a warmer sound you could go in a tube direction. 
 
If you want keep everything digital, what you've got is very good. Oh, and the only difference in sound quality between the Grace M903 and the M920 is DSD which is pretty much inaudible.

 

[MRC001]

  I have the Headroom Maxed Out Home and after 12+ years it's still sounding great! 
 
Personally I don't think you're going to really improve sound quality noticeably with any of the 3 choices. I went pretty extreme with my choices -Metric Halo ULN-8 and Prism Orpheus, (both +5000 pro interfaces when I bought them) and didn't really get the sound quality improvement I was searching for. With everything digital, if you want a warmer sound you could go in a tube direction. 
 
If you want keep everything digital, what you've got is very good. Oh, and the only difference in sound quality between the Grace M903 and the M920 is DSD which is pretty much inaudible.

Your situation sounds similar to mine and I appreciate the candid advice. Let me paraphrase you to make sure I understand what you're saying:
Stick with the current setup: take the analog output of each digital device directly into my analog headphone amp, or through the stepped attenuator into the power amp. There will be no noticeable improvement taking the digital output of each source device into a dedicated DAC/amp to drive the headphones or power amp.
 
Part of the fun of this hobby is trying it out - get one of these devices, plug it in and see if it does make any difference. Yet without a nearby dealer, it becomes a pain to purchase from places having 30 day return policies. So I'd like to narrow it down to 2 choices before jumping in.

 
BTW, I'm not looking for a warmer sound. I had a good SET OTL amp years ago and tubes were magical but not the magic for me. I like the way my current system sounds and really enjoy listening to it. Just wondering if a DAC+amp would (A) extract a tad more resolution without changing the overall character of the sound, and (B) simplify (replace 3 boxes with 1 box).