At best this would be a sideway's move. Agree w/russ69 upgrade the speakers. Triangles are easy to power the Nait 5si should have no problem handling the higher end speakers. In fact if you have a Triangle dealer near you see if you can demo some of the better speakers on your Nait at home.
Separates question/advice
Currently running an integrated, Naim Nait 5si, with a Rega P6 into Hagerman Trumpet MC phono pre on the analog side and Schiit Bifrost 2 on the DAC side, with Triangle Borea Br08 speakers . Considering going to separates but unsure if this would be going backwards or not...I am interested in the Schiit Freya + along with a power amp in the $1000-$2000 range (or could go cheaper and do a Schiit Aegir). Idea being flexibility to go tube on the pre with digital but also can go solid state when doing vinyl in case the phono pre is already plenty tubey sounding.
Anyone have thoughts or have owned and changed from a Naim Nait?