I have a pair as well and they are my absolute favorite mics. Besides overheads (on which they are amazing!) try them on acoustic guitars, snare drum (if you can take the risk of it being hit...yikes) as well as vocals. My personal favorite use is as a M/S pair. I've never heard a better M/S recording than with these mics. I just love those little babies to death!
The KM-56 employs nickel diaphragms which are very difficult to obtain. If you need a replacement KM-56 head, I have one. It is "new old stock" still in the original box, never installed. You can email me at Fletcher@mercenary.com if you're interested in this part.
I think you'll find the mics to be wonderfully clear, and exceptionally deep sounding. I have used them everywhere from vocals to acoustic guitars to one of two mics employed to record a drum kit. I've used them on loud guitar and bass amps as well as for strings, congas and pianos. A wonderfully diverse microphone with a sense of space and dimension rarely found in any microphone at any price.
Not to hijack the thread, but has anyone used both a KM56 and a Gefell M295 (also a nickel diaphragm)? I know it's probably apples and oranges, but any similarities which could be attributable to the nickel diaphragm? I've never used a KM56, but do own an M295, and like it a lot.
For the most part, the 54 is a single pattern 56 and the Schoeps M-221b is indistinguishable from the KM-56 from my experience. All employ an amplifier based around an AC-701/k tube, all employ nickel diaphragms, all have pretty much the same head grill assembly [though there is one version of the KM-56 head that changes patterns acousticly rather than electronicly].
As for the M-295... for my purposes it's "close enough for rock and roll". I don't have to worry about replacing a $750- tube and I know I can get a new membrane for the microphone should I require one. They're a bit clearer sounding than their tube counterparts, in some ways not quite as deep sounding... but overall, I'm more than happy with my M-295's and feel zero compulsion to ever own a KM-56 again [unless one fell into my lap for pretty close to zero dollars].
I use a pair of KM56, great mics for a lot of applications if the source isn't too bright. The KM56/256 in cardiode and the KM54/254 are pretty close soundwise. I think the price raised recently. Here I've found some for sale.