[Tube Preamp][Need Help]Could you suggest a tube preamp matched with a SS AMP?

Hi, everyone.

I am a beginner of this audio world. age 2 years + only.

my system now:

Source: Melos CDD-2 cd transport, Rega P3, also a laptop as a Roon bridge for music files.

DAC: Melos MAX-3 (for CD), RME ADI-2 

Preamp: Onkyo P304

AMP: Onkyo M504

intup sebsutivity: 1v

input impedance: 20kohms

Speakers: Klipsch RP600M

---> I am thinking to add some TUBE taste to the system. 

maybe a tube preamp is a good choice?

but, my amp input impedance is just 20kohms. it seems hard to find a tube preamp with low output impedance to match it. (around $1k budget, used or finished DIY is good to me.)

Could you give me some suggestion?

Thank you, guys! hope the good music and enjoyable voice always be with you!