Juha, I fully understand what you are looking for in terms of sound. I crave neutrality, resolution and imaging/soundstage but if this means a sound without substance or a stark sound then I can't live with it. It can be a very fine balancing act. The preamps you tried look ok but I'm not convinced they are the answer. If your system is otherwise not stark sounding and you don't need gain you could try a TVC (eg Promitheus) or Lightspeed LDR attenuator. If you need added warmth you will need an active preamp, arguably loosing some resolution - this is trade-off you seem to have found with the Velleman, but is it really that good?
There are lots of options......
TT 1 Trans-Fi Salvation with magnetic bearing + Trans-Fi Terminator T3Pro + London Reference
TT 2 Garrard 301 with NWA main bearing + Audiomods Series Six 10.5" + Ortofon 2M Mono SE
Digital Lindemann Bridge + Gustard R26 with LB external clock
Pre and Power Amp EWA M40P + M40A
Bass Amp & DSP Behringer iNuke NU3000DSP x 2
Speakers 1 Bastanis Sagarmatha Duo with twin baffleless 15" bass drivers per side
Speakers 2 MarkaudioSota Viotti Tower