^ thieliste, I haven't seen anything to support that. If you have, please share. The Pass Labs website's spec sheet doesn't provided a 4 or 2 Ohm spec. As much as I am a fan of Nelson Pass's work, Stereophile's measurements have been finding the Pass Labs wanting in this area.:
https://www.passlabs.com/amplifier/int-250
https://www.stereophile.com/content/pass-labs-int-150-integrated-amplifier-measurements
https://www.stereophile.com/content/pass-laboratories-int-60-integrated-amplifier-measurements