Add-on effects loop?

I have a tube pre-amp and tube power amp, neither of which has an effects loop.
I'd like to use a parallel effects loop between the preamp and amp, so that I can control the wet/dry signal from rack effects. Does anyone make a small effects loop with send/return and a mix level? I don't want to use a small mixer if I don't have to since I don't need the pre-amp and EQ circuitry that a full mixer has and don't want to risk modifying the sound; I only need the effects send/return portion. Is there such a device? Thanks for info.

Hey, yeah, the Nobels or Boss looks more what I'm picturing in my mind. I'll check them out further. Thanks.

I hated to spend a lot of bucks ($400 for that Rane; Rolls has one for about $200) and not need any of the other 8 input channels on a unit like that. I was hoping there might be something small with just 1-2 channels and an effects loop for $150 or so, small like a stompbox for instance, but so far haven't heard of anything. Thanks.

is take the power from a power supply (120 volt AC to 9 volt DC), feed the power to a handful of pedals via a chain of connectors called a "daisy chain". The PSM-5 is also a switch that permits you to use the effects loop that you can use with the PSM-5. As it is, I plug my guitar into a wah, an over drive pedal, a delay pedal and a volume pedal. In my effects loop are the lesser used pedals like phaser, compressor, flanger, octaver, chorus, distortion. This way, my signal does not always go through the pedals in the effects loop. Even my wah, overdrive pedal and delay pedal are bypassed with an A/B switch when I want my signal to only go through the volume/boost pedal.