Bricasti Designs M1 Upgrade Price List (upgrade to M1 Series II from M1 or M1 SE). I previously mistakenly referred to this upgrade as M21 from M1.
All Bricasti DACs have volume control. M3 has an optional remote. Remote adds $250 to a new M3, so negligible in a used M3 (no one prices their used M3 without remote for $250 less). Network may not be needed, but there’s not much difference in price between a used M3 with and without LAN. Maybe $500. Network adds value to a used M3, and makes resale easier.