[Lohb]

Hi, anyone out there currently running the Matrix M-stage Headphone Amplifier + Hifiman HE-400 together ?
 
I'm thinking of buying the M-Stage with the OPamp upgrade chip from the below selection with the aim of taming the upper brightness, bringing the mids forward (if that is possible) and extending the bass further if that is also possible.
 
OPamp upgrade selection is :
 
 
 
[size=x-small]Burr Brown OPA627[size=x-small]A[/size]P with Class A Biasing Mod  [/size]
[size=x-small]Burr Brown OPA627BP with Class A Biasing Mod  [/size]
[size=x-small]Burr Brown OPA637AP with Class A Biasing Mod  [/size]
[size=x-small]Burr Brown OPA637BP with Class A Biasing Mod  [/size]
 
I read NWAVGuy's website post on opamps and the 627 was ranked in his elite section with the clause that " Unlike the Veyron, there’s no built-in stability control—that’s up to the designer to get right. With a slew rate of 55 V/uS, the OPA627 demands very careful attention to PC board layout, power supply bypassing, parasitic inductances and capacitances, and reactive loads on the output."
I'm not sure if 637's are an improvement over the 627's with respect to synergy with the +'s and -'s of the sound signature of the HFM 400's.

 

[Mad Max]

nwavguy is saying that the OPA627 & 637 high-speed opamps are not drag-n-drop Lego bricks that you can pop into any circuit.  They require a circuit that is especially designed for them.  The M-Stage is designed for OPA2134 or other slow opamps.  I recommend OPA602BP, you will need two and a special adapter for them. Other good ones are OPA2209 and OPA1642 if you can find them soldered to a DIP adapter so that you can use them in the M-Stage.
You will need an equalizer of some kind to bring the mids forward.
If a particular chip lacks bass extension, a 0.1uF ceramic capacitor added across the power pins will probably remedy that, so long as it isn't a terribly high-speed opamp that overheats to hell and back in the M-Stage (opamps are supposed to run lukewarm, so when they are very hot to the touch, they are unstable).

 

[Lohb]

Mad Max, thanks for the techie input. I have no idea why the ebay seller guides buyers to those fast Opamps then.
I found the first one you said and there is a ready-made on ebay.
http://www.ebay.co.uk/itm/321078835394?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
 
I'm just trying to find the best amp for the HE-400's under about $300.
I was also looking at a few other cheaper boxes....
Audinst HUD-mx1 being one.

 

[beaver316]

Hey MN,
 
Dunno if i mentioned in the HE400 thread, but yeah im using it with the M-stage. Probably one of the best pairings you can get for the HE400 under $300. Sounds great to my ears, and im running with the stock opamp too. But I haven't heard any other amps though so not sure if im missing much.

 

[eyushy]

Hi I was looking to pair the Hifi man 400 with the M stage amp. How is the overall sound? I listen to all sorts from electronic music to Fleetwood Mac. Would it make a good pair for all types of music?
 
 
Thanks Marc

 

[eyushy]

I I forgot to add I like bass from time to time but read the Hifi man 400 were not that strong in that department. Does the M stage Amp improve the bass with these headphones?
 
 
Thanks Marc