Why Are There So Many Audio Research Reference 5SE's For Sale

Been looking for a tubed preamp with high quality balance capabilities. Was looking at the Ref 5SE's but there seems to be many available. Generally when you see that there is some kind of issue. Sometimes they want to move up the line to the latest or they just arent that good. Case in point when was the last VAC Signature you saw out here. The good stuff seems to be rare and when they show they go fast. Comments and recommendations welcome.

ebm - curious, what is the basis for your comment " Everybody dumping ARC buying VAC"? 

knghifi, well quite, I'm not criticising people who do upgrade, just point out it can be an expensive business and it's to costly for me..

 I have nothing but admiration for ARCs business acumen and I don't think three years between models is a long time. If users are persuaded the upgrade is worth it, so be it. I would be interested to know how much of their income is based on SE upgrades, which I recently did with my REF 75, and users working there way to the latest model, as against first time buyers

The AR REF 5SE needs a high impedance power amp, 100k or higher. I was using it in my system with Bryston 10B-SUB crossover which has 15k input impedance causing high frequency roll off and lack of bass. I advertised it and it was sold within a day. The new owner uses AR mono blocks and it sounds great in his system. Since then, I went to passive route but still keep the AR Phono REF 2SE. The Bent Audio slagleformer fully-balanced passive preamp (silver magnet wire version) is higher resolution than the REF 5SE and has zero background noise.
anwar "The AR REF 5SE needs a high impedance power amp, 100k or higher."

No, it needs 20K or higher, according to ARC and this site, which is consistent with my experience, too.