Seeking Advice on Amp/Preamp or Integrated for Thiel PCS speakers

This is important for you to understand, as it tells you what the amp needs to be able to do to get the very best from those speakers.

Stereophile: measured tests.
Thiel PCS’s impedance magnitude (fig.1) hovers between 4 and 6 ohms over most of the band, and drops to 3 ohms in the lower midrange.
Note also the punishing combination of 4 ohms magnitude and 55 degrees capacitive phase angle at 120Hz.
This is a speaker that needs to be driven by an amplifier rated into 2 ohms to give of its best. But at least that amplifier doesn’t have to be very powerful; the PCS’s B-weighted sensitivity comes in above average at an estimated 89.5dB

BTW which Threshold do you own??

This means an amp that while not needing many watts (50w will do), but it needs to be able to pump good current into 2ohms and remain stable.
Look for amps that can almost double their 8ohm wattage into 4ohms and then again into 2ohms, this will ensure you have an amp that will deliver good amount of current.

The Rogue Audio Sphinx didn’t meet this into 2ohms, as Stereophile would have stated it in their measurements.
I would suggest maybe a John Curl Halo Integrated (it has a ESS Sabre32 Reference DAC inside it as a bonus) or a Pass Labs Integrated the Hegal 190 is also maybe a goer.

Cheers George

This is really helpful, thank you.  Should have read that stereophile review closer to pick that up!

I used to own a S/150 but sold it long ago.

Would have been a good amp, if in top electronic condition.

Cheers George 

As George points out, a high current amp. Older Krell, perhaps?