nightfall OP
Vandersteen 5a’s
If you want the very "best" out of them
Would be good if you can find a impedance/phase angle graph on these. Then it will be easy to find what your Lam’s were lacking, wattage or current or both. As nice as the 6c33c’s (to me the closest tube to SS) are in paralleled SE they are still tubes with weaknesses.
Until we can see this graph it will be all guess work from those that haven’t listened to them with all types of amps.
Unless the an amp is recommended that does it all, like the 180w Gryphon Antillion.
https://gryphon-audio.dk/shop/power-amplifiers/antileon-evo-stereo/ Plenty of watts, huge current, and the ability to switch Class-A bias while listening, between 10w Class-A, 50w Class-A or 100w Class-A Great amp for Summer or Winter
Cheers George