I dont know but looking at a guitar and line/level its a millivolt signal with typical 50mv for a instrument and 750mv for keyboard or line level.
These values seem to vary a bit, especially guitar pickups with hard hitting the strings and humbuckers vs single coils which some site posted 350mv on a humbucker.
The Red Box looks like it has a -26db pad so that should drop the incoming signal a lot.
A Pod shouldnt require the RedBox and I would think the RedBox doesnt need the Pod.
Thats the whole idea of an Amp Simulator is going direct.
If I recall the Pod has an option of Amp Sim or Non Amp Sim, so with that you should be able to set the Pod to Non-Amp sim and then into the Red Box for the Amp sim then to the DAW.
Red Box
The RED BOX 5 provides one unbalanced ¼" (6.3 mm) jack input (IN) for line and speaker signals
Red Box
0 dB / -26 dB: Your choice of input gain level can make or break your sound. If it's too high, you'll get undesirable distortion. If it's too low, the noise floor can degrade your signal. As a rule of thumb, go with ž-26 dB" for speaker signals and ž0 dB" for line signals. There are some instances where ž0 dB" is the more sensible choice for speaker signals: The amp's master volume level determines the speaker's output level directly, so of course the signal level drops markedly when you turn the master volume well down, for example, when you want to record at home at moderate volume.
Looks like a simple unit, kind of Sans Amp type piece of gear. $99 and no programming required! hell yes...
Watching a few videos on this and it seems the Amp Speaker out is the input to the REDBOX, but also you can run a preamp out to it (send from an amp) then that is the input for the REDBOX.
A bit different than I thought? So you can drive it with some power if it can take a speaker amp out....
I dont own one so maybe someone will chime in with details.or chat with Sweetwater tech support?