Can rgb amlifier dimm led strip?

Hello, do you know if RGB apmlifier from ebay like this http://www.ebay.com/itm/Signal-Amplifier-For-RGB-SMD-5050-Led-Strips-Lights-DIY-Hight-Quality-12V-12A-/390621011599?pt=LH_DefaultDomain_0&hash=item5af2d39e8f one can still dimm LED strip or will it run on full brightness all the time?

will it run on full brightness all the time?

Yes.

However, you might be able to PWM the RGB inputs to make it fade but that depends on the internal circuitry of the device.