Highest value pre under 1.5k used?

used rogue audio RH 5 linestage headphone amp.  stereophile class A.  hard driving transparent and energetic.  

Just stretch a little bit and go for the Rogue Athena (no affiliation to the seller or to Rogue) currently listed in classifieds. It will trash anything else in this range, especially other Rogues.

+1 on having the QS repaired. You own it and like it. 

Easy, the Topping pre90 ($500) + Ext90 ($250, optional). Look at the preamp used by this Stereophile reviewer,

Upcoming review of the Topping pre90 ($600) on Feb 2022 Stereophile.

Go to Amazon and buy the NuPrime dac-10.

It has an outstanding preamp section...plus you get an excellent dac.

I've heard the preamp section in this dac, and it's a lot better than a lot of $2k preamps that I've heard.

If, you don't like it, Amazon has a very liberal no questions asked return policy.

It costs $1700.