zolko60

What do you monitor with MIDI sniffer? You should monitor HD500 output I guess (or HX midi Thru out). Vox Tonelab has CC transmiting switched off by default. If you check your controller is sending what you want and the receiver is set to respond to what is transmitted, chance for cooperation is huge. ;)

Hx native is software solution not meant to compete with DSP based products. This is why two way communication with MIDI world is not supported by the Hx plugin.
Guitar Rig is software solution meant to compete with DSP based products.  This is why two way communication with MIDI world is supported by the software and dedicated hardware controller is present.

Fair enough?

OK. I'll allow it. Line 6 can make it skin friendly at 4.5 firmware ;)

I understand. The Volume Knob is not related to your problem. You can not set it to attenuate USB outputs level. You have plenty of other volume controlls in DSP and output blocks.

Hmm... quality and volume. There are Helix users who claim setting volume knob past 1 o'clock (about -10dB) gives them harsh sound and there are users who swear that volume knob is a tone sucker ;) What I claim is 10-20dB of digital headroom is normal thing these days. You trade some S/N ratio for some peace of not monitoring levels all the time.

As the manual states: "Mic In Gain sets analog gain for the XLR Mic In jack". Mic preamps have from 0 to 70dB gain. 20dB gain is usually enough to drive a condenser mic to line level (+4dBu analog reference, that is -14dBFS BBC digital standard). In case of low sensitivity dynamic and ribbons 40-70dB is used.

1 hour ago, jbuhajla said:

why not turn the gain down on the DAW side for those two inputs

If you have clipping at output turning down any "gain " on input is pointless no matter if analog or digital.

It was hard to me to understand Helix gain staging behaviour. Now I know that Helix instrument level is about 11dBu full scale, 8dB lower than line level. It gives me -10dBFS input headroom. What I mean is the headroom of the loudest transients with classic 8kohm humbucker pickup. This level was used for all models gain behavior to get about -10dBFS headroom at output. Of course you can make it clip, but if you make first your preset with DAW metering or even comparing with factory presets you are safe.
The volume knob is only digital attenuator. As far as I remember it is even advice in manual to make patches at the clockwise position to avoid making amps loud and protect clipping with the volume knob. Helix is probably 32bit floating internally so there is some space above 0dBFS, but the converter is still 24bit brickwall.
There is however no way the assign the volume knob for USB outputs.

1 hour ago, Kilrahi said:

no desire to go buy the real one at this point. 

Sure. DMM is clumsy I would not buy it either, but speaking about models even Amplitube buckets are better. Sound Toys EchoBoy is almost a cigar.
Speaking of Andy Summers: Amplitube model of EHX Electric Mistress, another iconic BBD flanger, is awesome, when I compare it to Hx model I want to cry... but Amplitube CE-1 model is crap just like Helix one.

Yeah. It can be the case too. Boss CE1 used to have preamp clipping that some guitarists loved. Delays dry paths are usually not transparent at all. When I compare for my own purposes I try to avoid converters influence. To be clear - I do not like to criticize things. Some Helix models sounds better to me than their analog counterparts. In my opinion BBD models don't come close. I do not know if they could be modelled better in respect to limited DSP resources. UAD Boss CE1 modell is outstanding - how much Sharc DSP processing power it eats? I dunno...  :(

Yes I have listened carefully. If I wanted to make a video showing there is no important difference between EHX DMM and Line 6 Elephant Man I would do it just like you did. ;)
To make a video giving some justice I would make it like Shnobel.
If you seriously ask me for advice - please notice that grainy distortion  often called "chime" BBD chips deliver  Focus a little on how they are degraded with each repetition on longer delay times. Use some brighter tone.
BTW: I have Superlux HD660 and Beyerdynamic DT770. The difference is somewhat similar and yes I can agree HD660 can do the job. ;)

3 hours ago, GingerLefty said:

The differences are minor and really not an issue. (...) I am damn impressed.

Well I am not :( You can make similar shootout of Squire Bullet vs Fender Stratocaster Deluxe asserting the difference is not an issue. Yes, in some circumstances like you have created in your video it is not.
I am not talking about details, but all Helix bucket brigade devices are not modelled correctly. They are muffled, overfiltered and do not have that BBD chime. Now I have only Memory Toy to compare but even MT is superior to Hx BBD models. I know buckets are hard to simulate. Strymon is close but at the expense of high DSP usage. Avid Separates BBD Delay plugin is also good. Can Hx model do the job? Yes, just like Bullet can mimic the Strat.
Please take a look how Shnobel make various DMMs shootout - to show the details that can be important:

7 hours ago, niarolf said:

, "Helix LT sucks. Badly." "harsh and digital"

What can be asserted without evidence can be dismissed without evidence.
Proove it please. Get your favorite amps, connect them to reactive load and compare with the corresponding Helix, Fractal, Kemper models using the same monitoring device. Maybe all digital recordings sounds "harsh and digital" to you and you should avoid the sound recorded and propagated this way?
Whatever - maybe just try to isolate your problem instead of sharing alerting, sucking assertions. ;) It feels very harsh and digital to me. :D

Links to collections in the video description.

12. Swap USB cables.
13. Swap USB ports
14. Try with no USB hub and with hub
 

Unfortunatelly I am not OSX expert. I guess both drivers are Core Audio. If you can change sample rate it is "downloaded". Class Compliant one os 48kHz and can not be unistalled.
If crackling occurs at 512 samples buffer it is no good. It is huge already.
Maybe somebody OSX experienced can join the thread and help you.

You may google it ;)

Crackling noise.
10. Check if setting higher buffer helps.
11. Swap drivers. There are two of them: Class Complaint 48kHz and "multisampling downloaded"

Sure. It can be the case but don't give up yet.
8. All Returns if set to instrument level are equal to guitar input set to 1Mohm. Try to set them to USB, check if they work properly.
9. What kind of noise is that?

Isolate the issue.
1. Deagregate interfaces.
2. Check if round trip on Hx works (DI to DAW, DAW to Helix, Helix to DAW) and how it differs from monitoring direct.
3. Agregate again
4. Check if round trip works while agregatted.
5. Make some conclusions,
6. Change troubleshooting method if not succesfull.
7. Keep the forum informed.

Sure, it would be nice. One drag and drop instead of export/import the setlist. Automatic syncing through the Line 6 cloud would be even nicer. ;)
Some day... maybe.

I dunno but why not sync manually entire setlist? You can also keep it in cloud in case you have hardware and native in two locations.

AUX input has 10kohm impedance. If indeed Hx Floor mic input gives you too much gain you can try this. It has fixed gain, right? Is it the same as guitar input (10dBu=0dBFS)?
But please consider that feedback threshold is not the matter of preamp gain but how loud your monitor is set. It is better to keep about 10dB of input headroom and master volume lower than 40dB of headroom and master volume up.

There are some specs. 2kohm output impedance. Not really low, not really high. Does it only have 1/4" TS jack output?
It should work fine with Helix FL XLR mic input even with cold to ground connection. If you have DAW, you can check how loud Helix mic pre can drive it. 
I don't recommend guitar input or DI box.

What mic? What Helix? Why 1/4-XLR adapter? Why guitar input?

There are some problems with Hx class compliancy under Linux. There is a thread about it: