SS3601 Discrete Op Amp Reviews – Fostex HPA8

The SS3601 has been reviewed in the Fostex HP-A8 flagship headphone amplifier.

SS3601_in_fostexThe HP-A8 is Fostex’s flagship 32bit DAC / Headphone Amplifier model and features finely designed Analog and Digital circuitries as well as the epoch-making DSD audio
playback function. Housed in a gorgeous enclosure featuring glass front panel and black side panel, the HP-A8C is set to spark the interest of both high-end headphone users as well as PC audio makers, professionals and enthusiasts.

I first tried to characterize the sound of the Fostex with the stock OPA604 op amps so that I could then compare it to the SS3601 discretes. With the OPA604s the sound was quite good, with lots of resolution and details.  They had a wide sound stage with mostly neutral (slightly warm and
decorated) sound.

The op amps in the Fostex are positioned in the middle of a bunch of tall can type capacitors.  Fitting the Sparkos op amps was a tight fit.  I had to slightly file down the corner to make it fit correctly.  I had originally thought about trying out some Bursons or DEXA discrete op amps, but there was no way they would fit in such a crowded location.  The Sparkos op amps were the only ones that stood a fighting chance of fitting into my Fostex.

After replacing the OPAs with the SS3601 discretes, the sound improved considerably. The discretes gave a wider sound stage and had a more transparent sound than the OPAs.  The transient impact of drums was improved greatly.  The discretes had less sound coloring and gave the music a more powerful presentation.  Its a great product, Thank you!


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Discrete Op Amps

Fostex exterior

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