Yeah, first thing you need to do is troubleshoot them.
A couple things to consider:
1. The Creek - while well reviewed for its price range - isn't worth more than $100. If it is what isn't working right, you need to decide whether to spend more money to fix it (maybe find an independent repair person that will charge less), keep it for sentimental value, or sell it for parts/repair.
2. The Denon speakers - It's hard to tell without a model, but Denon isn't exactly known for speakers or for anything above upper mid-level components. Check the woofer surrounds to see if they're deteriorated - this could be a problem, although it shouldn't cause crackling (maybe voice coil rub could cause that, I don't know). More likely if the speakers are at fault for crackling a driver may be blown, or the crossover may need overhaul. In either case, it may not be worth the repair for you - but other people who love working on vintage stuff may be interested (or even fix it for you cheap).
While there are many fine vintage pieces of gear - my newest stereo components are from the early nineties - these aren't exactly desirable (or repairable) compared to much of what is out there. Spend some time looking at the Audiogon classifieds or the Audiokarma forums to see what you may be interested in, if you are still looking at getting better vintage gear.
Oh, and those "overbuilt" components - McIntosh amps, etc., etc. always have a plentiful supply of parts for repair. Adcom would be a good choice on a budget for such durable components - especially their amps.
Speakers, unless damaged through abuse, rarely suffer any effects over time other than the crossover components aging. Replacement parts are easy to find for them as well. Oh, and speakers (especially at the consumer level) have advanced very little in the last twenty-thirty years. Good used vintage models will always outperform new speakers at a given price point.
sp70.
