I will eventually be using the Down East Microwave 2MLDPA. It's made for the 6700 and has a pre-amp and 75 watt output. You can order it with or without the remote option. I ordered mine with the remote option which lets you control the amp and pre-amp from SSDR. I have had the amp almost a month and am waiting on SSDR 1.10 to be released as you can't use the amp without it. If you order without the remote option, you can use it now with the 6700 or any other low output 2 meter source.