So as a counter point to the Massdrop amps, I also bought one of these Audio-GD units used.  The R2R15 seems to have been replaced by the R2R11 which is more SMD based but it looks very similar.  So this cost 350$ new, is not balanced but has a discrete R2R dac, discrete headphone amp and can also be used as a single source preamp.  The Chinese version of the product page is still active:

http://www.audio-gd.com/R2R/R2R15/R2R15CH.htm

I must say it does look really fugly in real life (as so many of the Audio-GD product do) but it's amazing that they can do this for 350$. 

Does it sound decent with the HD800? I don't know if you're keeping any dynamic headphone these days.

Edited March 3, 20188 yr by Torpedo

I don't have a HD800's now but I can get a set to try out at some point.    I do have the HD650's so I'll try them out later when I find some time... 

The Chinese keep getting better and better at this R2R thing... heard the Holo Spring not too long ago and it was also seriously awesome. A nice alternative if one finds the Yggdrasil too aggressive. 

Sorry , dumb question, but Why should we be using R2R instead of SOC DAC chip?

Many people feel that R2R sound more "analog" than sigma delta DACs do.

While a lot depends on the specific implementation of both the D/S and R2R DAC (and the filters),  each can give you a different flavour for sure.

Some straight-off-the-spec-sheet D/S DACs in particular can be very harsh in the treble, for example. Of course, R2R dacs with inaccurate resistor ladders can sound pretty poo and indistinct in their turn. Main thing is to have a good implementation of whatever you like. I'm not sure that there's a type you "should" be using (D/S vs R2R, OS vs NOS etc.)- more that you probably should use a unit that sounds good. There's more than one way to skin a cat.

Me, I'm quite happy with my modest Gumby (it's effectively R2R, just the resistors are in-package in the DAC chip), but I'm sure there are a good few decent D/S DACs that I'd enjoy too.

Edited March 4, 20188 yr by Kattefjaes

Birgir, whenever you have some free time, we would love to hear your follow up thoughts on this amp.

Thank you.

I haven't spent any time with it recently as I constantly have new toys to play with but I'll get back to it at some point. 

For the price it walks all over the Massdrop and Monoprice garbage.  It's also far more useful, a dac (with a variable output too), a preamp and a headphone amp.