hey @titser marco! i usually use mine with a 1x12 cab. It's my main amp that i run in dual mono or stereo with whatever amp is in the venue.
I've used it a few times by itself na rin, basta naka mic yung cab. It sounds great direct to the board too on those amp-less situations, but make sure you
get a good signal in your monitors. Like you said, pwede rin sa effects return ng backline amp, or if you have access to the back line amp's
speaker cable, you can just plug the ethos straight to that cab. I've done that a few times especially out of town when i can't bring my cab.
Usual rule is to use the speaker sim when going direct to computer, mixing board/pa or a keyboard amp, and turn it off when plugging into a guitar cab or effects return of another guitar amp.
Hope that helps! Pochoy Labog of Malay has been gigging with an ethos amp too. 
When I first read arkeetar's reply, I was baffled as to who bh was when I realised what the letters stood for. I remember Vin Dancel mentioning that you were an Ethos OD user, and I just connected the dots right now!
In any case, I think the Ethos OD is really great tone-wise, as I found your sound about two years ago at McKinley Hill [the Cradle reunion show on Valentine's] more than satisfactory. Just a few more Qs, if you don't mind:
1. How does it take fuzz pedals? I plan on running an SD1, a Big Muff, and a RATright before it and then run the non-drive effects in the loop. The tricky thing with most modelers I've tried is that the impedance matching can be tricky: while the final sound might be good, bad impedance matching always made it feel like there was some sort of glass wall between the pedal and the amp/preamp input which made the feel too constrained.
2. How long does it take for Custom Tone to ship out an Ethos OD to MNL? And how much did you have to pay in taxes, shipping, etc. I know this can be a sensitive question, but cost ranges would suffice.
Thanks, BH!
PS - Still GAS-ing for that SG you have up for sale!
