Phono preamp question


I'm slowly trying to upgrade my vinyl system to something that could be considered moderately decent, not necessarily high end. I have an older full feature preamp and am thinking in getting a separate phono preamp. I'm assuming the phono preamp would need to be connected to one of the line inputs. Would my preamp be the weak link if I get a good phono preamp to use with my existing preamp? Can a phono preamp be connected directly to the amplifier? FWIW, the preamp is an Adcom GTP-750. Thanks.
kalali
My bad, I meant to add what I paid for my preamp & phono amp in the post above. I bought them both when they were about 10 years old for around 25% of their original cost. I wouldn't necessarily recommend buying anything that old now unless it was completely gone through, but wouldn't hesitate buying another 10 year old unit if it was a well built one. You should be able to do that for a relatively reasonable price if you so choose. 

Thank you all for the tips and recommendations. Even though I very rarely use this system, I'm having hell of a time to let go of it. These gears have been with me most of my adult life; the L40s since 1978. 

As a start, I'll follow dekay's great tips and look into a suitable replacement cartridge. If I find myself listening to LPs more and more, I'll consider an upgrade path for the rest of the gear.

Thanks again. 

My last 2 cents
seeing your budget ( now I see why you said the Simaudio 110lp was hight end )
go for one of the Chinese tube phono preamps
for under $100 .

vair68robert, thank you. I've decided to repurpose my budget towards a suitable/better cartridge that I can use with this turntable and move it to better turntable if/when I decide to upgrade the table.

I'll post a separate thread to ask for cartridge recommendations after I've had the opportunity to do some background research.