Cable acoustics Totem Forest

Honestly, as you haven't even finalized your system, I would just buy a pair of 10 or 12 gauge Belden from Blue Jeans cable to use while you get the pieces together.  They do a very nice job terminating the cables too.  I think I even have a pair of 8' or 10' cables around that I could lend you if you don't live out of the US.  Free of course, but you can pay shipping.  After you decide on what you want, you can start with more exotic wires if you like.  On another note, having owned the Forests and Hawks, I would not use a 300b amp with them.  They need a relatively powerful SS like the Plinius you are considering.  I've spoke with the designer about this and he agrees.  The Hawks, maybe, but not the Forests.  Enjoy. 

My local dealer use them with xlo signature 3, sounds amazing, 

I owned the FORESTS and ARROS simultaneously in a prior system, and I experimented with A LOT of cable contenders and pretenders.

in short, I migrated back to what the dealer had originally recommended: TOTEM’s own TRESS cables. As an alternative, CHORD ODYSSEY or RUMOUR.

that is not surprising because:

(1) the TRESS are essentially CHORD knock-offs .... both are silver plated OCC braided copper; and,
(2) the FORESTS are internally wired with the TRESS.

AMP

Plinius .... full stop. TOTEM FORESTS are very power hungry gear that crave a lot of grunt from high current amps. TOTEM has paired them with PLINIUS at past audio expos. Other similar choices they have previously paired with FORESTS include integrated amps  from  SIMAUDIO and AYRE. I would test-drive any of these choices well ahead of your other listed units.