This little bass head sounds amazing - loud and toneful - for its size and weight.
I'm using it with a single 15", 4-ohm front-ported cabinet custom built by Eagle Works in Portland, OR (now out of business). The speaker is out of a early 80's Fender (Emminence) horn-loaded PA cabinet.
The amp has been very reliable as my church rig for about four years. Recently the input volume control failed - the way it works is in the feedback loop of the input op-amp and when the control fails (open circuit) you get no attenuation and must control your volume with the master volume. Incidentally, the back panel of my amp shows a 3-84 production date.
At Radio Shack I found a stereo 200k audio taper Alps pot that I was able to adapt by wiring the two sections in parallel (giving the desired 100k value), using three separate wires from the front panel mounted pot to the circuit board pads. The original control's mounting bracket must be removed (unsoldered from the board). I found a different grey and black plastic setscrew type knob to fit the new pot.
I noticed that my stock & totally original amp had a bit of audible 60 Hz hum. I found in my spare parts box two electrolytic filter capacitors of matching capacitance and voltage ratings with the stock caps. I wired the two new caps in parallel with the stock caps and superglued the added caps to the PC board. Since the clearance from the solder joints on the new caps was close to the removable chassis top, I added a piece of double-sticky foam tape for insulation and cushioning. By doubling the power supply filter capacitance, I noticed a marked reduction of the audible background hum.
Earlier when I had 8-ohm speaker cabinets, I added a Switchcraft 1/4" two-conductor jack on the amp's back panel, wiring it in parallel to the stock 1/4" speaker output jack. The two hot and ground wires to the added "extension" speaker jack were soldered directly to the circuit board traces. The stock jack mounts directly to the PC board so its solder points were not accessible for this mod.
The 200RCB can be used as a preamp to drive a larger power amp. Although there is no 1/4" line out jack, the 1/4" 'send' jack works just as well. Also the 'dry' and 'wet' balanced XLR's also work well for driving a PA power amp such as my QSC RMX 850.
The 200RCB can be used as a power amp only, by patching into the 'return' jack outboard preamps such as a Sansamp Bass Driver DI or an ART TubeMP or ART TubePAC. These outboard preamps will sound more modern, but not necessarily better.
Easiest, of course, is to use the 200RCB as a bass head properly matched to a 4-ohm speaker cabinet. It's plenty loud for most of the electric bass playing gigs and jams that I do. It's tone is very warm and punchy. Perhaps similar to GK's larger bass heads of the era - the classic 400RB and 800RB.
Incidentally, the 200MB is a 1-12" all-metal bass combo based on the 200RCB head that I've reviewed herein. I'm pretty lucky to have located my well-used 200RCB for a quite low price. I think the 200 bass amps are quite rare, so if you locate one in good working condition, buy it. I sure like mine.
Thanks for reading and have fun playing the bass!