Best Pre Phono for a Colibrì

Could you suggest a pre-phono for a Van den Hul Colibrì 0,65mv at 500 Ohm Optimal Load Impedence?
I know for example I could not use a Lamm LP2 which has a 40 Ohm load impedence input only.
There are two friends who are currently using the Colibri and one has the Manley Steelhead and the other is the Heron. Seems to work for them.
The Pass XONO is as refined and quiet as they come, and is almost infinitely flexible with regard to load adjustments.
Zender, i have 2 Colibri's; an XCP .85 and an XGW .65. i use the Lamm LP2 Delux to great result. i primarily run the XCP.....which sounds die for dynamics and immediacy. very natural sounding and never any edge.

i also have the Koetsu RSP II, and recently sold my Insider Gold. the Colibri's smoke both of those cartridges on the Lamm.

optimal impedence is just Mr. vdH's opinion, not necessarily a restriction.
Thanks for your inputs.
Well loading impedence it's not just an opinion.

I could understand that 500 Ohm is probably not a precise value but I cannot immagine it could be well arranged with a 40 Ohm load maximum value.

OTOH I trust what you say and I will consider Lamm LP2 as well.