Would you buy a piece of gear with a defect?

Depends on the defect and the asking price.
If only left input of channel 1 (input 1 ?) is not working could be a faulty relay, diode or the switch for the XLR/RCA connection that could be fixed relatively easy. Otherwise the asking price seems a bit high and may prove that it is not a bargain.
You could check the possibility of asking Parasound first whether they have a record of this unit.

No!

Would you buy a piece of gear with a defect?
I’m auditioning a Parasound JC2 pre amp that the left input on channel 1 does not work.

"could be just the rca or could be the circuit or board, bad news if it’s multi layered"

Love it, get it cheap fix it myself and sit back and marvel at what I got dirt cheap, and if I don’t need it, sell it for a nice tidy profit.

In the case of this Parasound JC2 with one channel out, I would offer 1/3rd of what they sell for good used working condition.

There is a JC-2 on Audiogon for 1900, full working condition as a like for like comparison.

So $700-$750

Cheers George

if it's just one input one channel, its likely something bad between the rca jack and the switch, and likely easily fixed.  I'd worry a lot more if one channel didn't work on all inputs.

Any competent tech could diagnose and most probably fix it.

If it were me, I'd go for it, especially if I didn't need all inputs immediately.  

Have you looked inside? JC2 Manual Online (htguide.com) I'm guessing you don't have a schematic. Preamps are usually an easier fix than other components. I read something that this is an FET preamp, if so I'd be concerned about obsolete parts. Do a lot of research! I would offer less than George. Good thing is you have a channel that works, so if it's an open trace on a multilayer board, time and patience could serve you well.