I hear differences which I prefer using the AP1SE & PP.
Some notes:
When I ordered it Philip told me that he had just made some improvements to the PP. I prefer running an coax cable rather than directly connecting it. I also had issues with the sound cutting out due to a ill fitting BNC connectors.
I initial tried a 1m coax cable and ended up with 1.5m as it sounded better. The fact that the Nordost cable connects very well to the AP1 with its BNC connectors and the supplied true 75ohm gold plated RCA to the Hugo, would have helped no doubt.
What did it add?
It added a magical quality to the Hugo with more air and less underlying noise, although Hugo is excellent using the HD USB input I found the sound to be just a little hard. The AP1 combo gave it a flowing euphonic quality and lifted it to another level of performance.
Is it worth the $2,000 spend? I don't want to get into that argument. I was chasing the ultimate performance out of my Hugo. I feel that I have achieved that.
I am enjoying my music so much as a result of Hugo that I have decided to buy an end game DAC which arrives in 2 weeks. When the new QBD becomes available I will try that as well as I am enjoying the Chord house sound.
Looks like the direction I will be going.
Worth the $ or not I won't comment but if its what I'm looking for... I think it is a worthwhile investments and a good foundation for any system. Spending $5000 on an amp that we can't get everything out of it is worthless IMO. A Thai guy just drop a cool EUR100,000.00 on Zensati home theatre cable, so...
BTW, what is your end game DAC?