Krell FPB-600 or FPB-700cx - RCA vs. XLR Input


Hi,

I am looking to buy a used FPB-600 or FPB-700cx amp. I am wondering if I should stick with the FPB-600 because I will be using RCA inputs. I know there are adapters to convert to XLR, but is that a good idea? Isn't there an impedance mismatch or signal level issue? If that is the case, I would not be able to get the FPB-700cx to unleash it's full potential? One thing I will not do is buy a preamp with balanced or CAST outputs. Thanks for any knowledge on this!
hi_power
Thanks Richard. I just am not sure if I should go from RCA to XLR on the 700cx. That is my dilemma. I would also like to see a picture of the 700cx guts. I can't find it on the web. The inside of the 600 is impressive.
One thing I will not do is buy a preamp with balanced or CAST outputs.

Clearly the 700cx is not for you; in order to obtain all the benefits of this amp you would need to do just that, especially CAST, otherwise you are wasting your money.
[Clearly the 700cx is not for you; in order to obtain all the benefits of this amp you would need to do just that, especially CAST, otherwise you are wasting your money.]

Stevecham - That's what I was wondering. If the preamp signals aren't matched properly, you can lose an awful lot from the amp. I wouldn't want to spend that much and have THAT happen.
The Krell 600, 600c or 700cx can be used successfully with a RCA output preamplifer - some people even prefer this mode to the XLR or CAST mode. Input impedance of MCX models is 100 kohms that can match almost all known preamplifiers.
Tube preamplifiers known for having DC offset or DC leakage should be used with the internal coupling capacitors engaged.
"A one piece RCA-to-XLR adapter is available
from Krell Industries, to allow single-ended operation
using the balanced XLR inputs" - taken from the Krell MCX manual.

Microstrip,

I was also talking with Larry at High End Palace and he thought using the RCA to XLR cables would not be so bad. That's good. It leaves me with more options.