At the moment , I have a Hidizs AP100 and Sony A17 handy. I am terrible in describing the SQ - so please take my opinion with a grain of salt. I am using LZ A4 [Red + Blue] for the comparison.
Compared to Hidizs AP-100, XS01 has more warmer tonality.I felt the bass is bit more meatier, hits harder and it has great texture(not sure if this is the right word). Clarity and separation are very similar. AP100 has much treble extension , but I prefer XS01.
Compared to A17, XS01 bass hits much harder and clearer. For some reason I find A17 to be lifeless. XS01 on the other hand for me is exciting and makes me dance
Other Pros
- Swappable opamps and they are easy to access. (BTW I am using OPA627AP)
- Solid build quality.
- Has four digital filters like in other DAPS which has AK DACs.
- Two headphone outputs, out of which one is for hard to drive headphones.
- Barebone UI like HisoundAudio studio's , but much better, the extra two button(Home and Back) really helps.
Cons
- Does not play 24 bit FLAC
- No dedicated line out , but there two headphone output, one much more powerful than other.
- There is a slight cracking noise when used with sensitive IEMS while changing tracks. Most of the time I dont notice it.
- Barebone UI , this also means , no playlist or other features.
- No Eq
Hope this helps.