I also have the SMSL sAp-1 “Class A” headphone amp. It’s like 75$, and you do get a taste of “Class A” smoothness… But a subtle one. I got this Aune X7S for like 150USD shipped and I say, if you can get it for this price, please don’t bother about the sAp-1. Yes, going from any of these (Liquid Spark, JDS Atom, SMSL sAp-1) to the Aune X7S is a heccin huge upgrade.