Well, since I was so pleased with the Matrix mini i I decided to try their m-stage headphone amp. I went with the upgrade opamp BB627A. Total was 280. Been running it for a while and it seems to be a real nice value. Apparently it is a clone of the Lehmann black cube linear, of course made in China
Here are some specs:
Introduction
The M-stage is a fairly basic headphone amp. It features 2 sets of RCA inputs on the rear, which are selectable via a switch on the front panel. It also has a line out which enables the unit to be used as a pre-amp. Aside from the input selection switch, the front panel features a single 1/4” headphone jack and a volume control knob. A power switch is located on the rear, just next to the IEC power cable receptacle. It really is a very simple design. The only somewhat unique feature is the pair of gain selectors on the bottom. Users can easily switch from 0, 10, 18, or 20 dB of gain, independent for each channel, with the simple flip of a few dip switches.
Features
· New 2010 version with upgraded power transformer and redesigned circuit
· Powerful output that can drive high impedance headphones (up to 600 Ω)
· High quality components including ALPS VR, Nichicon caps, OPA2134 Op-Amps, etc
· 2 sets of line inputs selectable on the front panel
· Can be used as a pre-amp with the line output on the back panel
· Gain selectors can set 0, 10, 18 and 20 dB gains
· Solid build with aluminum faceplate and steel case
· Fully dynamic and well balanced sound on a dead quiet background
Specifications
Output Power: 200 mW / 300 Ω, 400 mW / 60 Ω
Input Impedance: 47 kΩ
Output Impedance: Line out 60 Ω, headphone out 5 Ω
Frequency Response: 10 Hz (-0.3dB) - 35 KHz (-1 dB)
Signal / Noise Ratio: >95 dB @ 0 dB
Distortion: <0.001 % (6 mW / 300 Ω)
Anyway, I sold the Grado I had because this offers as good, if not better performance with more flexibility. This might even be a good line level pre-amp in a nice budget system. As it stands it is a very good HPA.