ELAN Tube Amplification- All-Tube Professional Guitar Gear – Elan Tube Amplification MK5 -Single and Dual-Channel High-Voltage All-Tube Preamps – Travel Size Package, only 2 lbs 7 models to choose from- "Dino" for
Designing Tube Preamps for Guitar and Bass, 2nd Edition: Blencowe, Merlin: 9780956154521: Amazon.com: Books
How to Choose the Best Bass Amp | GC Riffs
Demeter VTBP-M-800D Bass Amp, Hand Wired (USA) with All Tube Preamp *In Stock! - Bass Central
Dual Channel Blackface-style Preamp for Bass Guitar