Which of the following preamps?

Andy

Of the list you gave - I am familiar with Conrad-Johnson. I call tell you that all their preamps have a tube-like quality to the sound - and are well made with great warranty to boot! Not knowing how experienced you are in this hobby - I will tell you that once you get over $1500 price range (new price) - the differences in overall sonics are minimal until you get into the $4K territory. That does not mean that you won't prefer one over the other, just that above that range you're more likely to be looking at one area of the sonics.

I use a Conrad-Johnson PF2 Solid State preamplifier with a homemade single ended triode amplifier. Yeah, the sound is sweet!! Hope this helps!

Studio 1

I own / owned CJ , ARC and SF . The only one that ever required service is the SF. They all sound great. The CJ is a little warmer, The ARC a little more detailed. Both great your choice depends on the associated components and the style of sound you prefer.

May I suggest you consider the AES DJH Super Preamp? Especially outfitted with Polk NOS tubes, this simple pre sounds outstanding. Currently, one is being offered on A-gon.

One thing to consider is that years down the road ARC and conrad johnson will probably still be in business and offering support. That's one of the reasons I listen to an LS-16 in my system. This is not necessarily a recommendation for your system. Weiserb's comments on the sonic signature of these preamps are dead on.

What do you think about Audio Research SP9MKII?

There is one on audiogon now for 750.