Oi! Thanks all for the feedback B)
… one of my best tips is to make use of the (free) ReaFIR plugin for managing unwanted noise. I have an old JX-10 whose outputs are a bit noisy; using ReaFIR’s “Subtract” function eliminates the noise/hum completely with no audible loss of quality to the sample. It can also be used for super-precise compression and EQ, as in, if you need/want to eliminate or reduce or emphasize only a very tiny frequency range, ReaFIR does it easily. It’s by far my go-to tool when sampling outboard stuff.
Thanks for the tip on ReaFIR, think I have similar plugins somewhere that can ‘learn’ the noise/frequency spectrum and subtract it from the output (fyi CDP tool also has processes that do this; specnu clean, specnu subtract), but I am not necessarily looking to clean up sounds, rather look for the crackle & pop between songs on vinyl
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I’m not sure if a patch bay is what you’re looking for if it doesn’t sum signals. My impression was that patch bays pass signals in one to one to one from front to back so you can choose where to rout signals, but without a good number of inputs on your soundcard, I don’t believe this is the right application.
I think a patchbay could work. Suppose you have one stereo input on your audio interface, then you can connect patchbay slots 1 and 2 to it and your gear to record on the other slots (all on the back of the patchbay). Then, whenever you want to record something, you need to patch this on the front of the patchbay into slots 1 and 2.
My idea exactly fladd, have the inputs from the soundcard on the first slots, other gear on the rest and be able to connect on the front of the patch-bay when necessary. I wonder though if there’s any loss in sound-quality, depending on cable (length/brand), patch-bay manufacturer? Probably negligible paranoia 
The only thing I am not so sure about is how patchbays handle microphones (especially if they need phantom power).
I guess the best solution would be to have a 4 inputs on the audio interface: 1 and 2 are mics, 3 and 4 are Line. Then you would have patchbay channels 1 and 2 for mics and 3 and 4 for Line devices. Just make sure then to not patch Line into mic inputs 
To be sure I will keep to the line inputs and use mic’s straight in the soundcard’s mic inputs, don’t want to batch-fry all my gear doing something stupid. According to a mate, you can run phantom power through a patch bay just fine, but keep in mind you can’t plug in or plug out a jack while phantom power is on.
A patchbay will be a big help. Here’s the one I use: http://www.sweetwater.com/store/detail/SPatchPlus
The switches matter, because they let you control signal flow. Basically there are a few configurations you’ll use, all where the default is that the signal plugged into back flows from top to bottom. Depending on the switch, you can split the signal by plugging into the top, or replace the signal with whatever’s plugged in.
If you don’t have switches, you’ll have to unscrew the top and take out some cartridges and flip them around. You will never do this 
The great thing about the unit I linked to is that the switches are on the front. If the switches are on top, you can’t get to them if the unit is in a rack, unless of course you have space above it.
I had an old neutrik one for years. I learned my lesson about normalling options, and accessibility of switching them. The Samson is tough to beat.
I don’t think patchbays offer phantom power, at least not until they get more expensive. You could get a preamp and run its output through the patchbay however…
Thanks for the link and info. Will be looking for a small rack to mount the unit in as well.