I added a 5uF/100V ERO Polycarbonate capacitor bypass to each of the 300uF output capacitors. That and a little break in seems to have 'opened up' the treble a bit. I brought the headphone amplifier over to my friends house - he is currently running an all tube OTL headphone amplifier built by me using a EF86 triode connected as the gain tube and a 6922 as a White Cathode Follower.
In comparison, the Starving Student has better bass control and sounds more neutral top to bottom. To my ears the all tube unit sounds a bit more musical, but that could be from the higher output impedance having a little less control over his 150ohm Sennheisers. The 'Starving Student' sounded better and better the longer it was kept on and really had great impact and detail. I could live with either circuits - but the EF86 unit cost $500 to make versus $80 for the Starving Student! Of course the EF86 linestage has multiple input switching, RCA outs, tube rectification and premium parts.
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