iPad directly into Amp - okay idea? or bad idea?


I'm beginning my journey towards building my first audio system, and off to a great start with a pair of B&W CM9 S2 speakers. Next step - I need to power them with... something. I've found several vintage McIntosh amps available (like the MC 2105 & 2205). I was targeting around $1-1.5k more to get my system up and running, and these would consume that budget.

I'm considering pulling the trigger and getting one of them and plugging my iPad in to play music. Then I'll save up for a little bit until I can buy a proper tuner (I need a tuner next, right?). I get that this isn't ideal, but I'm wondering if it's bad for any reason? 

Additionally, I'm not sure about the nuances of how an iPad's headphone jack increases/decreases volume. I vaguely recall from long ago that plugging an iPhone into a tuner's component input sounded bad unless the iPhone volume was on max. Is this true? And if so, would that mean it would sound bad if it were anything less than full volume going into the amp? Which would almost certainly be too loud, correct?

And if I'm totally off track here, then how I can make music on my iPad play on my speakers for around the same price? 

Thanks in advance!
perplexy
Try using an Apple Camera Adapter to get digital out of the iPad, then go into a DAC. For me the Schmitt Modi 3 ($99) does the trick, do not let its low cost or the money grabbers fool ya.  If you want a fun project, build a Raspberry Pi streamer/DAC combo using a HIfiBerry DAC+ Pro ($40), sounds nice.
Yeah you need a DAC right quick.  I use an Apple Lightening to USB 3 camera adapter (the one that allows you to charge your device while playing) from my iPad and iPhone into an Audioquest Dragonfly Red for my headphone rig and it took the sound out of my Apple devices to a much higher level.  Obviously lots of great USB DACs out there, but this is a relatively cheap and effective solution until funds allow you to move up the DAC scale. 
Another vote for the camera adapter dac route. Dragonfly red is very good. If you don’t need mqa, can live with 24/96 and you want to save a few bucks, check out hifimediy. Their $69 usb dac is surprisingly good.
I support the DAC suggestion and you don't need to spend a lot to get decent sound quality. As @gemoody suggested I would start at the Schiit Modi  3, the Topping D50s (has built in bluetooth) or the SMSL SU-8 which is fully balanced (if you lean that way).  I own all three and the SQ steps up in the order I listed them. There are better  DACs available from the likes of Schiit, Mytek or Chord but they don't come cheap and you are soon neck deep in diminishing returns.  When you get suggestions for gear that cost an arm and a leg just remember it's your wallet and your ears.
DAC definitely needed. Dragonfly Red a good choice for this modest setup. (Q: why is it that few if any in this forum, or any others in my experience, can spell the word "lightning," as in "a bolt of?" The word "lightening" means "getting lighter" -- as for a frying batter, or dawn of day, of a change of mood, as in "his mood lightened when the lilting voice down the hall caught his ear").