I haven't been impressed by THD clips. If you want that tone, you need to go with a marshall. You can have them modded. Roccaforte did my mod and it's great. There is also Dave Bray, Voodoo Amps and Mark Cameron that are highly regarded. There is also Scott Splawn, but Rol had one done and it wasn't what he thought. Great sound, but not THE sound.
I have a '72 Marshall Super Lead modded by Doug Roccaforte with his high gain mod. It's basically the preamp of his High Gain 100 watt amp. He is more expensive, but the quality of workmanship and tone is great!! Contact him at Roccaforteamps@aol.com and tell him I sent you.