Totem Model 1 vs Totem Arro

Model Ones are great speakers and as you've already found an improvement over the Arros.  If you get the itch for trying new speaker cables try some Analysis Plus.  Very good with Totems and i think you'll find them even a better match than Straight Wire..

Also, if you allow me to spend some more money for you lol get the Plinius 9200 integrated amp.  Its an older model but pairs exceptionally well with Model ones.  Also has a very good phono stage if you spin records.

I would suggest not going below the Oval 9's for a good match to the Model Ones.  I used both Oval 9's and Oval 8's with my Totems.  The 8's will give you better base and more transparency but the 9's are a better value, imo. 

Well if you had the 8150 then you know what to expect with the 9200.  Only with the 9200 you'll get so much more.  Plus if you're in Europe you're playing in 220v.  The 9200 in 220v sounded as good as their separates. I'm in the US and at the time I ran a dedicated 220v circuit just for my Plinius.  Never tried Truss cables.  Good luck in your search.

I'd be very careful thinking that Totems can be placed that close to a back wall.  While I know nothing about the new Bison line, Totem advertises that many of their speakers can be placed close to the backwall.  Over the years I've owned four (4) different Totem speakers and never found that to be true.  Quite the contrary, the further out into the room (up to a point) the better.