I would like to know what the input/output levels on my TonePrint pedals are. Also, the FX loop on my amp needs at least +4 dB in and out. Will the TonePrint pedals work properly with these levels?
The inputs/outputs on the pedals are meant to be able to handle above line level, that is to say all the way up to +10dB! Therefore +4dB is no problem and is typically how line level is described.
See this additional topic
Please see also this FAQ regarding the impedance