Paragon Model 12 A against Audio Research SP-8/10

That sounds very interessting at all.

To the dull sound that could be becouse of bad tubes or bad caps.

I have heard other people saying that they rebuilt it news, caps, new tubes, better modification get a more silent MM cartdrige and of course a net filter against dirty power.

Some others say it is still the best preamp ever made.

Well, I still can resell it if I don't like it.

I have a Paragon 12A. When using it I thought it 'sounded' pretty good. It is of course a vintage piece of equipment and perhaps not as quiet as a piece of modern state of the art equipment. In the context of its own era I think it was pretty good and factually I got a lot of good listening to it.

No. But I remember exactly how it sounded. Very dull and lifeless. If this is about getting something to fit a budget and not about buying vintage gear because you are a collector, I highly recommend you consider an passive preamp. There's no reason to hold your whole system back with a cheap active linestage. A passive can work wonders in a budget system.

Well, but did you have a direct comparisson to the Sp6/Sp-8??

I had the Paragon and wasn't all that impressed with it. You can make a case for buying a vintage tube amp, but I'm not so sure about a preamp. Newer preamps are a lot better than old ones. I would just get something current.