As
@Tex Irie has mentioned, Astell & Kern is also in Irvine, CA, which is in greater LA, with their contact info here:
https://us.astellnkern.com/pages/contact-us
So from looking at The Source AV’s demo area pictures, they do have Schiit DACs and amps ready for auditioning, but not all of them, as they have many more headsets to audition as well. Schiit has almost all of their products ready for demo, but with a more limited selection of headsets, so you can go to TSAV first and if you like their Schiit demo offerings, then you can head over to Schiit Audio’s area and look at even more of their product line. Dan Clark Audio has expensive offerings in the Stealth and Expanse, as well as their electrostatic (needs a specialized amp to power them) VOCE and Corina, but also less expensive offerings, like the Ether and Aeon. TSAV May have these DCA items available for demo, but I am not sure, so plan your trip itinerary in both LA and SD areas accordingly, carefully, and properly.