The Bass amplifiers that I love and have a passion for are all valve and when I get time I may list these and the differences to help you when looking for second hand items. Marshall Superbass, Fender Silverface Bassmans, Hi watts 200, Mesa Boogie 400 plus Ampeg V4B and the mighty Ampeg SVT are in my view are the best 6 bass amps made. Listed here is my Mesa 400 Plus which is a very versatile amp and easy to transport and has a fantastic all round sound.
When it comes to transistor amplifiers I have owned, Trace Elliot amplifiers over the years I have used for gigs where I need more portability. The series 5 Trace Bass amplifiers with the Hitachi mosfets are the closest sounding to valve amplifiers of all the Trace Elliot range. The one that I have kept for reason of portability is my trusted AH150 head which is listed here. The modern Trace heads and combos with the uprated 600 watt output section are amongst the best sounding amps out there. When I wanted a small combo I simply compared these with the Mark bass and the TC electronic item and concluded on sound and functionality the Trace wins everytime. The modern Trace Elliot items seem very low on the ground currently and I hope they will start producing these again shortly. I have a mint condition 715X combo listed that I have used at home and mainly for using an acoustic bass. This is a great sounding amplifier that is something of a bargain.