Amps are difficult to choose. These days options are limited when going into a store and hoping to find a two channel amplifier, that is affordable and of good sound quality, and reasonable power.
In order to give an example of what not to choose -
My Sherwood home theatre 5.1 amp (which I purchased very cheaply from Cash converters- just to try out the surround sound thing) is rated at 100 Watts per channel. It says so in the user manual. The amp weighs about 6kg. ( that says it all)
When I connected it to my Audioline AL-1400, AL-600 or AL-3210 speakers they just sound lifeless and completely flat.
Well - its not the speakers! It's the darn amp. That amp just sounds horrible. it uses a digital volume control, and I think that circuit is just sucking the life out of the music. I can run that amp at 100% volume and the sound is flat, undynamic, boring, and the speakers dont seem to play very loud.
I can remove that amp, and install my Kenwood KM-208 amp (weighs 8.8kg - and only has two channels) which is 150 Watts per channel, and that amp makes the sound jump from the speakers. Very dynamic, lively, clear and LOUD :)
I wouldnt even dare run it at full power, it would break my ears and probably the speakers. :)
I've also connected my Audioline speakers up to some 25 Watt, and 16 Watt vintage Sansui amps, and they also sound very dynamic and clear. they wont play as loud as the 150 W Kenwood, but they still have all the dynamics and detail that I want and need for 90% of listening.
So if your Audioline speakers arent sounding that great, its probably your amp. Power isn't necessarily the issue, unless you like playing music super loud. A quality amp of even modest power should make any Audioline speakers sound clear and dynamic, because Audioline speakers are very sensitive. Meaning they will play loud with only a small amount of power running into them.
10-15 Watts will be enough power for most people during daily listening at safe levels. For "party" volume levels a 150 Watt amp is more appropriate to prevent clipping the audio waveform and burning out your drivers.
Suggestions are hard to make, but I'd err on the side of saying that any home theatre multi channel amp isnt going to be great because they are trying to pack in 6 cheap channels into the space where you can only fit two (good) channels.
So, my suggestion to power your Audioline speakers is to go with a second hand two channel amplifier of between 100 and 150 Watts. Something from the 1980's or early 1990s.
Generally I'd recommend Kenwood. Technics. or Pioneer based on their price for performance ratio. -If you find an amp that looks the business, read some reviews on them. Audiokarma website usually has good reviews and personal stories about older gear.
If you want to buy an amp from the 1970's make sure it has been professionally serviced and that it is working 100% perfectly.
Valve amps are a potential option for Audioline speakers but their (generally) low power is only suitable for people who listen at low to moderate levels. Valve amps generally have a less grainy sound than transistor amps, and often succeed in presenting more fine detail than the average transistor amp. The amp shown below is currently manufactured and puts out 20 Watts per channel and costs $3,999.
The boutique nature of modern valve amps make them suited to people who have the money to buy one, and the time to fidget around with finding the best sounding valves. Their high voltages, hot and often exposed valves make them, in my opinion, not recommended for people with young children around (although covers are available)
It's difficult to find new two channel amps these days with a decent quality to price ratio. They seem to be either cheap and nasty or very expensive. There is not much in between, which is why I'd recommend a second hand amp bought locally. If you really want something brand new, I very apprehensively mention the online only brand - Emotiva. Their price to performance ratio is very good, but my apprehension is due to that if something goes wrong with it, and you need to send it back to USA for warranty repair, given the weight and size of the amps, this is often going to cost you over AUD $300. Even with their "reasonable" prices, buying one is certainly a gamble. Tread with caution, and dont blame me if something goes wrong.