What Class A is better? SUGDEN FPA-4 or PASS LABS XA-25

I`d like experiences of the gurus.

Before I went toward tubes, I looked hard at both but didn't audition. So I cannot give you the experience answer you're looking for. However, one audio dealer which a lot of people respect is Gig Harbor audio and they're very nice people who carry Sugden. If you called or wrote them to ask why they deal in Sugden, they might add some data to your inquiry. Yes, they're a dealer so they'll be biased toward what they carry, but sometimes these conversations yield nuggets. https://www.gigharboraudio.com/
I have the Sugden A21se and I love this amplifier, so much grunt it defies the power expectations of most, I’m using it with KEF R3’s and it’s a very nice pairing, the Sugden is just very musical and clean. 
I have tried out a Sugden A21SE and a Pass Labs INT-25. I kept the Pass Labs. The Sugden is nice, and the Pass is nice. I felt the Pass was a better product, though more expensive so it should be. For me, sounded better and was built with a true heirloom quality. The Pass Labs INT-25 makes all of my music sound wonderful, some of it magical. Probably the most pleasing and satisfying integrated I have owned (coming from 30 years of experience with ARC, Cary, Ayon, McIntosh, Devialet, Line Magnetic, Luxman, PS Audio, Vinnie Rossi and many others). With all of that said the Sugden also brings up a similar sound in Class A but the Pass does so with a bit more expansiveness and detail. Bass on the INT25 is remarkable. 
I’ve owned both, multiple pieces. I like Pass Labs allot but ultimately preferred the Sugden iA4 Masterclass - which I did not think would be the case. It’s insanely good. Addictive. I’ve owned allot of gear and I think the Sugden is great gear with no compromises. I would recommend some good horn speakers, maybe even tannoy Cheviots (not horns but wow). I currently have it hooked up to a pair of JBL 4349’s and the soundstage is solid and 3-dimensional. Just insanely tangible. I got the Sugden iA4 as a holdover for a Line Magnetic 845-Premium (Stellar unit), I already have one at another house and liked it so much that I wanted one for my Chicago office. There’s a long wait so I got the Sugden, once again as a holdover... Well it didn’t take long for me to cancel the order for the LM 845-Premium, which is a MAGICAL piece, and decide that the Sugden was easily just as good. I wouldn’t say it bested the LM 845-Premium but I’d say it was equally as enjoyable. Pass is great... but both Sugden iA4 Masterclass and Line Magnetic 845-premium where better. Ive had Mcintosh mc462 with a c2700, Pass Labs INT-250, Primaluna evo 400 separates, Bel Canto, Luxman 590axII, AR GSi75, hegel, golden note... a decent amount of gear. In conclusion it is the Sugden iA4 and LM 845-Premium that are gonna stay.