[scannon18]

Currently I drive my Denon D2000s from the Fiio E7/E9 combo.  However, I am looking for an upgrade and have come up with the following, any input from owners would be appreciated.  I am mostly interested in: clarity, instrument seperation, soundstage, and there can't be any roll-off with the bass.
 
Schiit Asgard:  The website says this amp is specifically made for low impedance headphones, so it seems like it would be a good match for the 25 ohm denons.
 
I've read great things about the Audio gd NFB 12.  This would be a plus because it has a great dac.  However, I've heard that the soundstage is reduced with this amp, and I really want something to show off the soundstage of the D2000s.
 
The Matrix M-stage is also highly regarded.  If anyone has powered the D2000s through these (or D5000s) comments please!
 
Also, there's been a lot of talk about the O2 amp from JDS labs, comments on this amp are also encouraged.
 
And, lastly, are any of the above amps really a clear upgrade from the E9?

 

[liamstrain]

the E9 is usually not considered ideal for very low impedance headphones (25 ohm)... it has a fairly high output impedance (10), comparatively, making it ideal for headphones over 80ohm (the rule of 8 times, is the usual standard). 
 
So I think any of them, would give you better bass control and definition, over the E9, just due to better impedance matching and electrical damping. 
 
What is your budget? Maybe there are some other worth while options to consider from that? 
 
Of the ones listed, I'd probably consider the M-stage (get the version with the USB) as the best value for a high quality amp, with the flexibility of at least a USB dac input on an under $300 budget. 

 

[phandrew]

I had the NFB12 for a while to try it out and i didn't notice any drop in soundstage at all. The DAC in the NFB12 is worth it over the M-stage imo and it's also cheaper.

 

[scannon18]

The whole ouput impedance thing has me on the fence.  On the one hand, I can understand the rule of 8 from an electrical standpoint; it makes sense on paper.  But my denons seem to have real synergy with the Fiio equipment, and I have heard similar things from others.  I think paper measurements are important, but not as important as what you hear.

However, the E9 also compromises soundstage, at least compared to the E7.  This could be because the E7 has an output impedance of 0.15 while the E9 has an output impedance of 10.

 

[scannon18]

Quote:

I had the NFB12 for a while to try it out and i didn't notice any drop in soundstage at all. The DAC in the NFB12 is worth it over the M-stage imo and it's also cheaper.

Which headphones are you using the NFB 12 with?  Yes, the dual 8741 chips are enticing
 

 

[phandrew]

Quote:

Which headphones are you using the NFB 12 with?  Yes, the dual 8741 chips are enticing
 

DT150 and AD900 at the moment
 
Also the NFB10 is coming to me soon as well. Want to try out the balance ports