Pioneer a109 w/ 90db speakers

Hi guys,
i've been looking around this forum for a while trying to get the answer for my question. I got some mixed answers and just want to make sure I got it right.

I'm about to buy a pair of speakers, it's a really good deal on some good speakers (I assume). The speakers specs are:

Configuration: 2-way bass reflex
Power-handling capacity: 100 / 160 W
Impedance: 4 – 8 ohms
Frequency response: 30 – 52 000 Hz
Recommended amplifier output: W 30 – 160 W
Efficiency (1W/1m): 90 dB

Now I'm trying to get an amp. As I'm on a budget I'm considering the Pioneer a-109. Specs:

Continuous power output
(both channels driven at 20 Hz to 20 kHz)
T.H.D. 0.1 %, 8 Ω.....................................30 W + 30 W*

DIN Continuous power output
(both channels driven at 1 kHz)
T.H.D. 1.0 %, 8 Ω.......................................40 W + 40 W

Total harmonic distortion**
20 Hz to 20 kHz, 15 W, 8 Ω................................0.08 %*


My biggest concern here is if there is anything wrong with this setup.

Reading the speakers specs it seems to be ok (minimum amplifier output = 30w). I'm just confused about the 4-8Ohms bit and the two specifications for the power handling capacity: 100w/160w.

My guess: while operating at 8Ohms the speakers can handle 160w and my amp will provide 30w. But when operating at 4Ohms the handling capacity of the speakers drops to 100w and my amp would provide with 60w. Sorry if I'm talking the biggest nonsense in the world. It was just a guess.

Another doubt is the difference between "Continuous power output" and "
DIN Continuous power output".

Thank's in advance, I'm getting overwhelmed by all the information I'm reading recently. It's been fun, tho