Finally got my Boss WL-20L. Happy to report, there's no difference in sound quality from using a cable. It works great with my Martin GPCPA4 which has a Fishman F1 analog pickup, and with my Martin D-15m which has an LR Baggs Element pickup. Great results plugging directly into the S1 Pro (I do prefer it with the guitar tonematch, as opposed to the tonematch off), or running through a Bose T1 tonematch mixer (with the S1 tonematch OFF). The transmitter did not interfere with other plugs going into the back of the T1. No latency issues, excellent signal to 50' (which is as far as I tried it). Did not work at all with my Ovation guitar which has the OP30 preamp. The battery light flashed on and off and it sent a matching oscillating thump to the speaker. All 3 are active systems, all sound great cabled, so no idea what's causing the Ovation issue. Otherwise, I'm happy with the WL-20L. It charges fully in about 3 hours, and is good for around 10 hours on the receiver, 11-12 on the transmitter. The plugs on both the receiver and transmitter have switches that turn off the units as you remove them from the guitar or amp - no popping when you remove or insert. However, if the receiver battery dies, it makes a loud pop when it shuts down. Fortunately, lights on the receiver warn you at 2 hours and at 30 minutes before end of battery.