Yeah, just drop the voltage down. Replace the R1 (150ohm) to 240 Ohm and it will output 6.458V. That will dim down the lights and provide a greater contrast.
Here's a calculator to play with output voltages:
http://diyaudioprojects.com/Technica...age-Regulator/
Just keep in mind, you will need to use a value that is actually produced as a resistor. Just because you want to use 175 ohms doesn't mean it exists, or it may be really expensive.