Not that I know of. Marketing hype has pushed the 'bigger is better' concept so hard for so long that a company that tried to sell a feature-rich 5 Watt amp would get killed in the marketplace.

Because a multi-channel preamp is going to cost a lot to build, it's easier to sell it as part of a $1000 100 Watt amp than to build it into a 5 Watt amp that would be priced at about $400. I paid about $400 for the 3-channel Peavey Rock Master preamp, so a front end like that might bring the cost of a good 5 Watt amp up to the $500 mark!

It would not be a big seller initially, due to severe resistance to the concept in the marketplace, so it would be a long time before sales volumes allowed lower prices. {deep sigh} :p