Need opinions on 4/5 channel amp (<$250), and 6x9s (<$125)

[elitesystem]

1) Is it better to use a 5/6 channel amp and run the sub off it, or just upgrade to another 4 channel amp and buy a mono amp for the sub

2) If going for a 4 channel amp, I was thinking of a Diamond Audio because I've heard good things about their SQ. I don't usually turn my volume up too loud so I figure 50W per channel should be fine. Should I look at any other brands instead (if I am getting a 4 channel and mono amp separately, I'd like the 4 channel one to be <$200). Would just a cheapo Profile amp be fine for the sub in that case?

3) If going for a 5/6 channel amp, the only ones I've found in my budget are the Infinity reference series for around 250. Are these amps ok, and will they be better than my mtx?

4) For 6x9, I was gonna go for the infinity reference 9613i 3 ways. What other ones would be good in this price range?

Any advice would be appreciated, thanks!

[atl530i]

Get a Hifonics ZXi8008 5ch amp.

55wRMS x4 @ 4 ohms, 110wRMS x4 @ 2 ohms

Sub channel does 150wRMS @ 4 ohms or 300wRMS @ 2 ohms. Go for a dual 4 ohm sub and parallel the voice coils down. You can find these on ebay for ~ $200