I'd like to start off by saying that you have a set-up indicative of a lot of Pet Store info. However, I used to breed Balls and Boas and had 19 Herps at one point with 4 breeding pairs.
I would have recommend an Under the tank heater pad. And get rid of the Aspen. Too many times I have had a ball dropped off to me that wasn't eating only to find a piece of aspen lodged in their mouth or upper throat. The aspen getting in the mouth doesn't have to happen when their eating but Over time I am sure you will see your ball "yawn" or completely unhinge his jaw and reset it. During this process Aspen can and will enter his mouth in your Current setup. Aspen lodged can cause upper respiratory infection. In addition the smell of Aspen can easily mask Snake Urea, Hindering your ability to see that the aspen has been wet. Urea and Aspen don't get along very well. Most times the aspen underneath grows mold and fungus, Also leading to Respiratory Disease.
A lot of people tend to go overboard with balls in regard to Basking lights. Many use them to actually heat the entire enclosure. However I must remind you that Balls are nocturnal animals and very rarely if at all will you find them in the daytime out basking in the wild. If you want to replicate their Natural lifestyle while maintaining the warm dry climate they need to thrive in the wild I would dump the lamp and get a Heat Emitter.
His hide should definitely have a top. Your hide is a good size as he fits snugly inside of it. But their should be a lid of some sort. Again, Balls tend to Burrow into an abandoned home of a rodent they have recently consumed. These homes have roofs.
I also avoided Heat Rocks like they were the plague. Heat Rocks have had a history of malfunctioning, and burning if not killing animals.
Lastly make sure he can submerge his entire body when he wants in the bowl you have. I couldn't tell from the pic if he could adequately fit in the bowl. If you notice he doesn't soak on his own you may be inclined to soak him in a bucket once a week or so for 15 minutes. It helps at shedding time.
Some things I was always a big fan of.
Great Article
http://www.anapsid.org/ball.html
ESU Reptile Rock Dens
Heat Emitter
Reptile Carpet
Under Tank Heater.
Mike