Hi. I need help to choose preamp for my system.

If you choose the Krell pre-amp to mate with your Krell amps, I'd suggest A-B'ing balanced versus all-CAST. Anytime I've heard Krell gear, all-CAST is the best sound option.

Thanks everyone for the input. My question is how good is Sonic frontier line 3 on bass vs SS preamps like Krell, etc

From my experience, Sonic Frontier is a great match for Krell. Haven't auditioned the latest Krell 202 but was never a fan of Krell preamps.

I had a Krell KSA100s with SF SFL 1 and SFL 2. FPB300 and FPB600 with Line 3/3SE+. Line 3 has a very low output impedance for a tube preamp so it will work with a SS amp.

IMHO, I would buy an used Line 3 for ~$2K and get the SE+ mod from Chris Johnson @PCX. I wouldn't waste $$ on a SE ...

Line 3SE+ also benefits from tube rolling. My favorite is Amperex Phillips SQ e88cc and Ediswan CV5065's.

I would think the Krell pre would work really well with the Krell amps.Just a thought.

I forgot to mention that my choices are between Krell kct and Sonic Frontier line 3. Thanks for inputs.

Depending upon your budget and your desire to buy new or used and your desire to match/not match your amps, etc....I'd suggest Classe CP-500 or CP-700, SimAudio P7 or P8, Krell KCT, Krell 202 and others.

The world is your oyster. If you like oysters.
Seriously If you like the EAR Phono try thr EAR line stages.

It would be helpful to know your budget, but a great preamp for the money is the Parasound Halo JC-2. It works especially well with solid-state amps. For a tube linestage, I highly recommend the EAR 868--drive, body, liquidity, suppleness, and soundstage.