Hi Batemans
I know Cadence somewhat, and used to own a pair of their speakers.
They are Indias (only I think) high end company.
Cadence speakers originally reached plaudits for the successful marriage of electrostatic tweeters with conventional mid/bass units. They worked quite well (I heard most of the range)..
For me though, the Cadence speaker sound was perhaps a bit too plumby, a bit too rich sounding, a bit lacking in high mids, where I normally expect to find a bit of sparkle.
The cadence amps came later, and Ive only read about them on the cadence website, never used them.
Croft pre's go for about 300-400 used, and are popular. I dont think you'd have a problem getting 300+ on ebay.
2 x 100 monoblocks for 600-700 doesnt sound bad value. I dont think you'd get much more than this for them personally, as you are dealing with an unknown amp brand in the UK, and there really isnt any dealer back-up out there.
Personally, Id listen to them and see what you think. Its a lot of valve power for not much money.
Again, I would not be worried about faults developing - valve amps can usually be repaired (whoever made them originally) because they are not that complex inside by and large.
Finally, I think 'worth 1600' for the monoblocks is very over optimistic for a used price. The 600-700 I mentioned before would seem nearer. perhaps 800-900 on a very very good day.
If you really want a lowdown on them, take some digital pictures of the insides of them, and you'll get some better feedback on the design.
Finally, 2 x 100 w monos and a pre is great if you have inefficient speakers. Is this what you have? If not, a lower power SET integrated amp might be prefered, I know a great one for about 1,200.
Chris