Thanks to jcarr of Lyra for interesting information.
He wrote: "The Lyras will work OK in tonearms of 10~12g eff. mass (for example SME Type V, Technics SL-1200G), but will sound progressively better as the effective mass increases. Normally I’d suggest 16~18g as the sweet spot"
I run a Lyra Atlas (standard high output version) on a SME V arm. Should I add mass - even 6 g - to the arm?
Thanks for info!