Test bench power supply

6 amps won't be enough... what budget are you trying to stay in?

I use a Shumauker 200 amp battery charger and a nice AGM battery and test out just about anything just fine

I use cascade APS power supplies. They can be gained together in parallel with the same models for up to 6 for increased current. Regular battery chargers can produce some dirty power even on a battery. I learned that the hard way. http://cascadeaudio.com/power_converters/power_converters.htm These are used behind 12 volt electronics displays and in comp cars to power the amps when the car isn’t running. They also do a good job of charging a battery without over charging it so long as you keep the voltage on the lower setting. 

I have an ASP 30 I might be willing to sell. 

Im in Australia so I use a AC/DC Converter which churns out 40amps and has enough juice to run two amps and a head unit. Loud enough for my garage needs.