Schmalle

This. Audio signal transmission is not about maximizing the transmitted power - which would be impedance matching. It's about maximizing level (high voltage) at the input with high fidelity (low current). This is called high impedance bridging / voltage bridging.

Plug your headphones in the headphones jack.

You are right in that an amplifier that needs to tame the signal it carefully amplified to provide a low signal for FX gear isn't that great of a design. A modern amp like a 5150 III i.e. has a tube preamp, an intermediate OP amp based FX loop/preamp send/headphone buffer stage and a tube power amp to do that. Is there a way to use a multimeter to find out the signal voltage and impedance of different points in the signal chain of an amplifier? - Yes, you need a multimeter, a potentiometer or a collection of resistors and a test signal generator for sine waves (a synth/PC/phone will do the job). Then do this.

Something like this?: 60 Hz hum That's most likely coming from a not lifted ground to P.A. which was powered by another outlet. Push the ground lift switch on your Helix when you send a signal to P.A. or ask the sound guy to lift ground on the mixing console.

The USB cable completes a ground loop that acts as an antenna. The loop: socket 1 - power cable - Helix - USB cable - computer - power cable - socket 2 - socket 1. This has 2 effects: 1) Electromagnetic fields inside this loop will be picked up. So if you minimize the area the loop spans you minimize the noise it can pick up. Laying power cables in parallel next to each other helps, also using the USB ports in the back of the computer are usually better, because the loop now doesn't contain the inside of it where the cpu and other stuff produce electromagnetic noise. 2)The loop can also inject mains hum. That can be minimized by plugging PC and Helix into the same wall outlet using a multi socket. Of course not closing the loop is best which can be done by using an USB isolator, but those aren't cheap. If you use a laptop you can unplug it's power supply and prevent a ground loop that way.

HX Edit 3.01, HX Stomp 3.01 Exported patches miss command center settings.

My personal settings for an ambience reverb that I tend to forget it's until I turn it off: Plate - default values with those changes: Decay 2.6 HiCut 6.5 Mix 20% I listen through studio monitors in moderate levels.

Should work if both amps share the same ground. Plug them into the same power strip / multi plug adapter to make sure.

That's normal since the tip of the cable now touches both button paths. If you pull the cable on the HX Stomp a little until it rests (which is exactly the length of the tip) you can test FS5 function as well.

Mine works fine. You can test the button 2 by pulling out the plug on the Mosky a little until it rests naturally. Now it should do whatever button 1 did before.

After setting Global Settings > MIDI/Tap to MIDI PC Send OFF, did you repower your amp? Otherwise it might have been in PC mode and therefore didn't react to CC messages. Did you set the dip switches on the amp to MIDI channel 1?

Increase the reverbs High Cut. Think of it this way: you mix the dry signal with duller reverbed version of it which makes the sum of both duller, too.

'Super glassy', 'harsh' and 'thin' are all adjectives that indicate a lack of bass and/or low mids.

An A/B recording would help to objectify the described tone loss.

A TubeScreamer has an input impedance of about 500kOhm or higher and an OD1 about 1MOhm.

To give you an idea of the amount of signal loss due to DA/AD conversion: Try a patch cable in the FX Loop directly connecting send and return. Then A/B the sound with and without the Loop in the chain. As for me I don't hear any other than a little extra noise.

Could you name those overdrive pedals you use? Have you used a preset with only the FX Loop in it? Have you set the input impedance to 1MOhm in the input block to make sure it's not an issue ?

It's probably a level issue. Have you set the Global Settings > Ins/Outs > Send/Return to Inst? When it's set to Line the signal your overdrives receive are pretty hot.

... or a detailed instruction.

Please share the preset and if you can record the phenomenon.

TGP-member John Mark Painter has a thread by called replicating my favorite pedals with Helix that might be of interest.

Are splits and mixers before / after the cabs the same?

@AlchemyStrat Post a patch of which you are sure the problem occurs.

Sorry, my answer applies to HX Stomp only.

Make shure Global Settings > Ins/Outs > Return Type is set to Return. If it's set to Aux In the return signal will be directly forwarded to the outputs.