I definitely like the 405-2, plenty of grunt and a bit more slam than the 303 I have.
The pairing with the Quad 34 I find a bit on the clinical side - the 33 has a bit more of a mellow, euphonic and 'tube-like' feel to it when connected to the 405-2 .... but less detail
The 606 is an itch I'd like to scratch at some point .... bit skint now but a couple more months without cigs should pay for it ;)