The specs are easy to find, except the output voltage they don't usually show that spec on avr's.

I must get a great a preamp that can deliver more than the 3.4 volts it needs for the kKrell to deliver 600 watts into 8 ohms. Wow should get alot louder.

I’m using the Denon Avr5800 as the preamp. I dont know if I’m driving to full load but I have Denon cranked all way up 06 db

Some might think that if a digital source can output a voltage of 2V, crank the volume of the Denon all the way up to +6dB the pre-out should output a voltage of 4V, BUT THAT’S NOT ALWAYS THE CASE!

https://benchmarkmedia.com/blogs/application_notes/19947905-the-audio-path-in-consumer-grade-audio-products?_pos=1&_sid=1805d554a&_ss=r

I must get a great a preamp that can deliver more than the 3.4 volts it needs for the Krell to deliver 600 watts into 8 ohms.

👍

Thanks for the link very informative 

So did you ever ck to see if the jumpers are connected on the Krell"s balanced inputs?? They look like large rounded staples looped from 2 of the 3 pin outs. If there are none of these connected you will not get the drive your expecting even with a real deal preamp.Tom