Speaker advice for Mac MC2505

I'm soliciting advice for a friend -- I'm as close as he has to an audio advisor. Sad, I know, but what can you do? For many years he's been the owner of a Mac MC2505 amp and a C24 pre, and he needs new speakers. A thread here at audiogon says that the 2505 can be tricky to match with speakers, but I can't say I grasp the issue. Hence this thread.

He listens almost entirely to classical and not typically at very high volume. The room is probably about 12x20, I'd guess. He wants to stay under $1000 and is willing to buy used.

Two things: 1) Specific suggestions. I was thinking of suggesting some Totems - Arros or Dreamcatchers perhaps - or Green Mnt Europas. But they're all 4 ohm, and I don't know if that would be a problem for the 2505. And so ... 2) Why is the 2505 tricky to match speakers with? What should I (he) be looking for, or NOT be looking for?
I had a 2505. Any speaker I ran with it was fine. Just pick the power tap closest to the ohms required. If in dought, always err to the low side. A 2505 will have NO problem with 4 ohm speakers. I even used it with some that dipped to 2 ohms in the bass range. Remember, you are dealing with a McIntosh! They can take it!!
p.s. You can get a nice used pair of Paradigm Studio 60s V2 for under a grand that work very well with McIntosh gear.
I agree with Hpims. The only thing to remember is the 2505 is 50 wpc out of any of the taps. It doesn't "double down". So don't buy any old Apogees. A speaker I'm enjoying now is the Omega Super 3. It lists for $550 but it's small and he could add a cheap sub to fill in the bottom. 8 ohm, 93db and no x/over, it would sound great at low or high volume with the 2505. It's reviewed at 6moons. Good luck.
I own A 2505 and must agree that they do well with almost any high efficiency speaker. You get 50 watts and thats it, 50 watts, the auto transformers see to that. They synergize well with heritage Klipsch but for a low level classical music guy they may not be his cup of tea. They can be a tad boxy. For $350 try a pair of vintage Heresys. The amp definately did not like pushing my bigger JMlabs.
Thanks. It sounds as if it's no big sweat. Also and BTW, double checking the Europas, they are closer to 8 ohm. 4-5 ohm in the lower frequency -- I didn't read carefully.