A simple low cost tweak for your system is to clean the connections. Interconnect cable, speaker cable and tube connections will oxidize over time to the point where signal degradation is occurring due to improper electron transfer. This will happen even if the materials in the connections are exactly the same. Dielectric corrosion will occur between dissimilar materials in air which besides looking ugly will degrade and even stop electron transfer over times if left unattended. The manufacturing process can leave contaminants on your connection, be it grease, dirt, protective coating or who knows what 
All of these situations are robbing your system of musical information and in extreme cases can be causing distortion of the signal (our musical information) Use a high quality connection (contact) cleaner. Don’t cheap out here and buy a bargain, they can cause more problems than they solve. A web search will find you lots of info for contact cleaners, I like and use Nu-Trol.
I will at this point also point out a common joke of mine, clean your ears The final connection of musical information to your brain. Q-tip type cleaning while it feels good is actually over time building up a block of ear wax (not sure what the correct term is) that is bocking what your ears are receiving as musical information. Go see a specialist on ear cleaning, not expensive and it could be the ultimate tweak you ever make in audio !. Also known to be healthy for long term hearing. I’ve checked into bees wax cleaning, will likely try soon.
A fifth connection not commonly considered is your musical source connections, for vinyl, it is the inner groove on the record, brushing a record does little more than pushing the dirt further into the bottom of the inner groove, get a record cleaner that gets the dirt out and don’t use a brush anymore that pushes dirt in (they all do!) For quick cleaning prior to playing I use the NAGAOKA Rolling Cleaner CL152, it is around $50 to your door from a seller in Japan on eBay, and for deep cleaning I use our Opera Consonance RCM, which uses vacuum to remove dirt from the inner grooves. (Ok, kind of expensive, sorry about that).
CD Players or anything with a laser pickup should be cleaned, using either a commercial disk based cleaner or if you are handy with electronics, you might want to consider going inside and getting to the 2nd laser pick-up inside the transport and get a Q-tip on it to remove any dust build up.
Thats it, happy cleaning equals happy listening
Cheers,
Ian
Ian,
I have actually found a safe and effective home ear cleaning system. It is sold by CVS Pharmacy and costs only $5.99 US.
Info at:
http://www.cvs.com/CVSApp/catalog/shop_product_detail.jsp?filterBy=&skuId=440621&productId=440621&navAction=jump&navCount=3#prodDescCont
This Ear Wax Removal Syringe has a flared insert that fits into the ear canal, but does not allow the tip to be inserted far enough in to contact or damage the ear drum. the tip also has a nozzle on the end of it that diects the fluid in 3 directions onto the ear canal walls, which also protects the ear drum from damage. Finally the tip also had drainage slots in it so the fluid can be sprayed in and flow out without removing the device.
I is it with just warm (not hot) water to flush out my ears. It usually takes two or three syringes full of water to complete the job, but when they are clear you can immediately hear the difference even in the water rushing in and out of your ear. Once that happens go back and listen to you system. The difference will not be subtle. My doctor has always commented on how little wax I have in my ears and I heard a huge difference, so I can only imagine how big of a difference it would make for someone whose ears tend to retain wax.