Pass Labs HPA-1

I am trying to decide on a SS pre-amp to pair with a First Watt SIT-3. Budget is under 5K. 

I am thinking about the HPA-1 headphone amp used as a preamp and am curious how it compares to the XP-10 or XP-20. 

I would appreciate any input/feedback from people having heard these to compare. I am coming from a tube integrated amp which is great but lately have been wanting to hear more detail and resolution as opposed to tube bloom. 

Not quite the same comparison, but there was a period of 12 months about two years ago where I was strictly using headphones.

I used the HPA-1 as my headphone amplifier. When I transitioned back to a proper 2 channel rig, I kept the HPA-1 for a while as my preamp.

While it did perform admirably, it wasn’t nearly as good as the Pass XP-12 I demoed, and even less so compared to the XP-22 I ended up purchasing.

The HPA-1 is a great headphone amplifier, and a solid preamp. It has limited functionality as a preamp however, having no remote control option, two inputs, and unbalanced.

If you aren’t focusing too much on headphones, I would go with one of the dedicated Pass preamplifiers.

The SIT-3 has extremely low gain for a power amp, the spec being 11.5 db and Stereophile’s measurements indicating 11.3 db. In contrast, most Pass amps (and many others as well) have specified gains of 26 db.

Based on the 11.3 db gain it can be calculated that the SIT-3 will require an input of about 3.3 volts to reach its specified 18 watt maximum output power capability into 8 ohms.

The HPA-1 has a specified gain of 8 db, which corresponds to a voltage multiplication of 2.5 times. Assuming the 8 db figure applies to its preamp output, that means the source component would have to provide a voltage of 3.3/2.5 = about 1.3 volts for the amp to be driven to full power, ***with the volume control set at max.*** Most cartridge/phono stage combinations will not provide that much voltage with most recordings, while most digital sources will just provide modest margins relative to that figure when expressed in db.

So unless your speakers are highly efficient or you use digital sources providing output voltages that are significantly greater than average, or you listen at particularly low volumes, you would probably find yourself on the verge of running out of range on the volume control.  With at least some recordings if not many.

The two Pass preamps you mentioned have specified gains of 10 db, which is just a bit better. The SIT-3 requires very careful system matching as a result of its low gain.

-- Al

Thanks, kingdeezie and almarg.

Yes, the lack of a remote and the lower gain on the HPA-1 are points against it for this particular application. I won't be running a phono cartridge, just A DAC with 2.2V output. 

I think I can strike the HPA from the list of contenders.