I was totally happy with the Matrix M-Stage’s performance, and it has officially taken the spot of my new favorite entry level amp. Moreover, I’ve been listening to the M-Stage with the Hifiman HE5LE, and though the Hifiman EF5 is a superb pairing with the HE5LE, somehow the solid state man inside me keeps on pluggin the HE5LE with the M-Stage amp.
As I briefly mentioned in the M-Stage review, replacing the stock opamp with a top-grade opamp like the OPA627 took the M-Stage’s performance to another level. Then, purrin commented on the M-Stage review that I should bring the performance of the M-Stage even further by biasing the opamps into Class A. Removing the input coupling caps of the M-Stage would also clear up any coloration brought by the capacitors, but I didn’t do this part because I use the M-Stage with a variety of different sources.
Anyway, this is a pictorial guide for those of you wanting to try biasing the opamps into Class A on the M-Stage.
First you need to open the top panel by removing the four screws on the sides.