Bring my own preamp to an amp demo?


I'm going tomorrow to demo a Bryston 4B3. I have a PrimaLuna Evo 300 preamp and Harbeth 30.2 XD speakers. The dealer suggested that I use a similarly priced preamp that he sells, but if I want to hear the amp with my specific preamp and the speakers I own (which he sells, and I bought from him) I need to drop it off when he opens and come back later because he has other appointments booked and needs time to connect my PL preamp, and maybe (I'm guessing) get it warmed up. I'm also going to listen to a BAT VK-56SE, and he suggested I keep an open mind and listen to an Einstein Integrated amp and thinking about selling my PL Evo 300 preamp. He wants me to have an open mind, and said he has a lot of customers that like and bought the Einstein with Harbeths. He also has an Audio Note amp demo for me to listen to as well. He's not a fan of PL, but is happy to work with me.
Bring my preamp or not?
Previewctwith3
ctwith3 
after demoing the Bryston ask to demo the Big Belles amp and Belles preamp
You need to demo the gear for a few days  in your room with your system.
@ctwith3 

 Did they give you a demo to take back to your home or did you take your equipment in? 

I'm not in the market for a preamp.
I have bought from John...  he is a character but I think he is passionate about audio for sure 

I ordered something he didn’t stock, he was the closest dealer but he was confident I would like it and said I could return it if I didn’t 

I thought that was fair.     Turned out to be one of the best pieces I’ve ever owned.  Talk to him he took good care of me , I think mainly because I talked to him and he is a no BS guy....  didn’t try to upsell or steer me to something else.   Give him a call