rd2rk

In Global Settings/Pedals, try reversing the polarity. The way it's worded in the manual it would seen to only affect the Exp Pedals, but as the jacks are dual function, maybe it'll work.

No, he's not. L6 was modeling real world pedal board behavior. It was widely criticized in the community as a poor design choice, and that's why it was changed. Search for posts here and over on TGP by @Tito83. There's extensive discussions on the topic. He was even credited for the change in the Update notes.

Silly human! I'll bet you think that words have "meanings"!

Are you SURE that you're on v3.11 of the FW? If YES, do a factory reset. If that doesn't work, reinstall the FW v3.11 and FOLLOW ALL THE DIRECTIONS including the seemingly redundant factory reset AFTER the update. If it still isn't working, call support.

In Global settings INS/OUTS, set the inputs to LINE. There's no separate Input pad on the HXS. You can also try using the L/R RETURNs set to LINE. There's also the Input Gate on the Input Block.

Yes, but if you're looking for big bass sounds (to a point, it's a guitar amp after all) or sounds with movement, you're better off with a PC212+.

Or, you could just use a FS or Snapshot to turn it on/off as necessary. You can also create the preset with a Helix amp/cab/ir and do the same with those. No need, really, for an extra pedal in the FX loop unless you prefer it.

Try a different USB cable. Try a different USB Port.

Since both inputs are always ON, you would need to put one of the guitar's OUTS (piezo probably) into one of the RETURNs (left probably, since that's TIP). Then put the RETURN Block on Path B with the Piezo amp/effects. In Global Settings INS/OUTS, set Send/Return 1 to INST. Change the SPLIT Block to A/B and route the INPUT signal 100% to A. Pull the MIX Block DOWN to create SEND 3/4. Set 3/4 to MONO. Assign the LEVELs at the OUTPUT Blocks to Snapshots. Snapshot 1 - OUTPUT Block MAIN L/R LEVEL 0db OUTPUT Block Send 3/4(TIP=3=L) LEVEL -120db Snapshot 2 - OUTPUT Block MAIN L/R LEVEL -120db OUTPUT Block Send 3/4(TIP=3=L) LEVEL 0db Snapshot 3 - Both OUTPUT Blocks Level 0db Run TS cables from L/Mono Out to the Boogie; SEND to the Benz. I've attached a demo preset. NOTE: Snapshot 3 Output/Send Block levels may need to be adjusted from above to account for your desired mix. Another way to do this whole thing is to assign the Output/Send Block Levels to an Expression Pedal with the MIN/MAX settings opposite one another. That would give you mix control from the Exp Pedal, but would not be instant as in the Snapshot method. Since you can't assign a parameter to more than one controller, it's either/or. There may be other ways to do this, but this is what I came up with. adagostoSS.hlx

If you put the delay just after the amp, with the MIX set to 100%, you'll only hear the delayed signal.

It would also be helpful if you attached the offending preset for analysis.

As @psarkissiansaid, first make sure you're getting the requisite power from the mains. This can vary depending on time of day and other factors. If the power is good, you probably have a flawed Powercab. I use a Cyberpower UPS that shows the exact incoming voltage, and makes up for deficiencies with battery power.

I also have the Sony MDR-V6 which are 32 ohm IIRC, and similar to the 7506. Those sound harsh to me. They're also closed back vs the AKG being open back, which I prefer. If you do a search on here for headphones, there's a number of lengthy discussions. Also over on TGP in the D&M forum. You could probably save yourself a lot of time and get a much wider range of opinions by checking those out.

No, not designed for any of that.

I use those same cans (K240) with my 18i20 and they sound fine.

Sometimes, hitherto undiscovered quantum particles from galaxies trillions of light years away will pass through our primitive electronic devices, causing random fluctuations in the force. Perform a factory reset.

I'm intimately familiar with that particular conundrum. The only solution I ever found was to have a good friend whose ears I trusted come to the gigs as "adviser". Problem was, by the time I bought him (and his GF) drinks all night, I could've hired a sound man!

That's the one I'd heard of. Consider how much time you've put into the configuration, vs how long it takes to connect a pair of cables. Also, consider how happy you'll be when the next MAC OS breaks Soundflower..... Sometimes the simple HW solution is the best solution.

First, the latest version is v3.11 for both Helix and HX Edit. Make sure the versions match. For Input Level, you get a choice of INSTRUMENT or LINE. If you're plugging your guitar directly into the Guitar Input, you want it set to INSTRUMENT. There's also a PAD switch, intended to be used with active (or very hot) pickups. If you're using passive pickups, you PROBABLY want it OFF, but some people like it ON (me for one). When you highlight the Output Block, the level that shows on the meter can be adjusted in many ways. The Channel Volume on the amp is one, the LEVEL of the Cab/IR block is another, adding a gain block at the end is another, the output level of a Studio type compressor at the end of the chain is yet another. And then there's the question of the AI. Usually, with the Input Gain on the AI channel all the way down, you're at UNITY - IN = OUT, no AI Preamp boost. If you set the Output (using all gain stages, including Output Block Level) of your Preset to where the gain meter on the AI is just hitting YELLOW, maybe an occasional flash of RED when you dig in, (Green-Yellow-RED), you should be good. You might want to search the forum for GAIN STAGING, there's lots of posts.

You can't use Helix via USB on a MAC while simultaneously using HX Edit? I don't get it. I'm a PC guy. and I do this all the time. I assume that you're using Helix as your Audio Interface? I don't know about Garage Band, but this works fine with Reaper, Ableton and Cakewalk, with both Helix and HXStomp. Maybe If you describe your complete signal chain, HW and SW?

The difference between using a BOOST vs a GAIN block is that NONE of the boosts are truly "clean", they all affect the overall tone in one way or another. The difference between simply using the block's bypass vs level is that, depending upon what the Snapshot does, you may WANT the added level of fine-tuning that using the block's level allows. This: is a good thing to consider, regardless which method you choose to use. Also, using an EQ, a traditional method going back to analog pedal boards, allows you to (as @SaschaFranckmentioned) slightly boost the mids to help your leads cut through. Going back to using a boost, you may find one that does this naturally, but using an EQ gives you more fine-tuning options. As with everything Helix, lots of ways to skin the cat.

Place a Gain Block at the end of the signal chain. Assigns it's LEVEL to Snapshots. Or Assign the Output Block Level to Snapshots.

You'll need to run Helix direct to Scarlett. What @PierM was probably going to say was that the MAC Input won't map internally to the output, same as on a PC. There are "pipe" programs available for MAC which make that possible, but a pair of cables is probably a lot easier.

The last thing I can think of to try. Take the TS ends of your Insert cable and connect them directly to the Left and Right Returns. If you get stereo, the problem is NOT the HXS. If not, then, assuming that you've tested the insert cable for continuity, it's your external FX or the preset that you've decided not to attach for analysis. At that point you can open a support ticket so that the support tech can tell you to attach the preset for analysis.

Also, there's a switch on the back of the TimeLine - is STEREO IN/OUT selected?