Mystere IA21 int amp vs Audio Space Ref 3.1 300B

I am in the market for a tube integrated amp and I was wondering if anyone has or demoed the Mystere IA21 or the Audio Space Ref 3.1 (300B) int amp? I kind of wanted to stay within the 4-6K range. Any other suggestions?
Not really comparing apples with apples here. Maybe comparing the Mystere which is an EL34 or KT88 amp with the Ref 3.1 (KT88) rather than the 3.1(300B) might be more informative.

I haven't heard the Mystere but have listened to the Ref 3.1 (KT88) and thought it was stunning driving a pair of Living Voice Avatars. Very neutral for a tube amp providing more detail than you might expect and very good integration top to bottom. The bottom end is reasonably tight though doesn't match some ss amps I've heard. My regret was that I'd already bought the Cayin A-88-T which, while also an excellent KT88 amp, was playing in a different league to the Audio Space (at an appropriately lower price to be fair). I live in Hong Kong so it may still be somewhere in my future!