@christianb5s4 Not sure about home demos. I have only bought some items online from them. I have gone to the store for some audio events. I definitely recommend that you make that relatively short drive up to Covina. I think the Duo XD is really great stuff. I tend to dislike tubey, warm, and smooth sound. However, the Duo XD works for me. You never get any fatigue and keep thinking that this sounds so nice.
I should really have bought it for my Magnepan LRS+ speakers, but the size of the amp is a bit big for my office. I may change my mind since I have a friend who I visit and he lives 3 miles away. If I do not have an amp the next time I visit I will visit the shop and maybe make an impulse buy.
I love the amp with a neutral preamp (my Benchmark LA4). Most will use something warmer and maybe demoed with warmer gear. I may not have bought it if I heard it that way.