I must admit... I've always used the HD500 for tweaking through HD500 edit. I've never had the squeals... and I got really worried when I read about it about 3 weeks ago.

I play connecting the HD500 through a Fender Princeton 112 into the Power Amp In input. So my main volume is fully controlled by the HD500's master volume... at the amp I have no volume control at all !

So if the HD500 sends this very high squeal signal... I'm gonna have 65 W of squeal right into my face and ears. Generally I tweak patches in a small room I have, in front of the computer and with the amp by my right side (as I play at the stage).

I'm simply not brave enough to give a try before having at least a few positive feedback about this fw. I don't want to experiment 65W in my face with the squeal... then I could say that my ears would bleed!!

(and also don't want to damage my brand new Eminence Swamp Thang 12" speaker recently purchased and installed on it).

It's just too risky for me, as I don't have no volume control at all on this specific situation . I'd have it in full power, 65W right into my face with no volume control

I was having this problem very frequently when using my HD500 with HD500 Edit and Reaper. In my scenario the squeeling would always occur when selecting an amp model on a brand new patch. It only seemed to happen when Reaper was open and armed for recording, but I didn't do significant testing to prove this. It happened to me pretty frequently and I was pretty much gaurenteed to get that awful screetching at least once or twice per session.

Yesterday I downloaded the new firmware and updated HD500 Edit and spent a good few hours recording with Reaper. I didn't have any problems at all! I was creating new patches, tweaking existing patches, swapping set lists, pretty much everything I would expect to be able to do. The new firmware seemed to cope with this without any problems, and you can see the POD LCD now shows a "Sync" message when it's tranferring data to/from the PC.

So far so good, but I will test further and post back if I run into any problems. In the meantime, if you're brave enough to try your POD with the new firmware, I would recommend using low volumes to start with, just in case!

After this recent update, all squealing has seemed to disappear... I have clocked about 3 - 4 hours of HDEdit and all is good... So far...

I hate to be the bearer of bad news. I updated to the 1.43 firmware (the proper way). Had two loud events that had a scratchy fuzz sound. Then another like the one with the 1.40 firmware. I started a discussion, Here is the link.http://line6.com/support/message/358135#358135

I would like to update my post. I reloaded the 1.43 firmware shortly after my last post. It seems to have gone better this time. First time, all my presets sounded thin with no low end. This time it was much better. I would think that the problem has been solved.

Has this issue been fixed yet?  I just ordered an hd500 and I play with headphones a lot and this issue scared me....

Good to know.

So no one else has reported the squealing after the update?

I'm currently doing a little research on HD500 vs GT100, trying to decide which to buy, and reading through this thread has been a little discouraging.

I'm not overly concerned that there was a software bug (these things happen) but I *am* concerned with the manner in which it was handled by Line6. Whenever I review a product for purchase I pay close attention to reported issues AND the details of manufacturer response. Resolving an issue may take time, but responding to a complaint doesn't. My conclusions from this particular thread are:

1. Unless my problem becomes widespread I will likely be ignored.

2. If I receive a reply it will likely be a generic one no matter how detailed my report may be.

3. The Line6 approach will begin from a position of the user having done something wrong.

Are these conclusions correct? Doesn't matter; that's what my research pulled up and that's what I have to go on.

Companies should keep in mind that it's not just existing customers who follow these stories; it's potential customers as well. The internet is not new, and word gets around at the speed of electricity which can be good or very bad. I'm still considering the HD500, but certainly not with the brand confidence instilled by my prior purchase of the UX2 (which continues to work well, btw).