Jadis dpl2 users

Jadis dpl2 preamp, users, please inform me if this pre is phase inverted. A friend of mine bought it without papers and needs to know. Also if it is phase inverting pre , your speaker cables change done in the amp or in the speakers.

Please replies only from Jadis dpl2 users or dealers who realy know.

Thanks in advance

anyone who knows ?
Hi George,I would think phase would be easy to detect. Listen both ways and check vocals and bass. Both would be dead center,with a tad more bass when correct. Changing phase is done at the speaker end.
Thanks Avguygeorge,
I know this is the only way to be sure but it's a friend's system and he is not so expereienced.

Now as for changing phase (speakers or amp), I've an inverted Cary slp98p and I changed the phase on the amp and not the speakers (that is I know) what other friends have to say on this ?