How big is your room? HK6550 is rated at 50 watts per channel. Sonodyne 2605 floor standers might be a bit 'okay' to drive, but might not get the best out of them. for 40k budget there are plenty other options including bookshelves, that you may want to look into.
Finally audition before you dive in to buy anything.avoid impulse.
Taga seems to be a good line up of 5.0 and bookshelf speakers which are rated at 6 ohms load....since HK6550 is rated at 50watts 8 ohms....you should be able to connect speakers upto 120/140watts at 4/6 ohms load easily.