Rogue amps and PrimaLuna are also in your price range, and worth auditioning. I own a Modulus pre and used it for 10 years with a Classe CA-200 amp with Vandersteen 3 speakers. I would think Your system already leans to a fairly nice, laid-back sound. When I switched to a tube amp, my choice was the McIntosh MC275, which sounded darn good with the Vandies.
For more richness, you might look at Conrad Johnson gear. The MV-50/52 etc. for instance might be just the ticket for you, and save you some money too versus some of the other suggestions above. You need to be a little careful with the Audible Illusions, since it has relatively high output impedence. You should look for a power amp with higher input impedence. Also, you may be disappointed with the bass you get from your tube amp transition compared to the Classe. Everything's a trade-off, and you need to decide what matters most to you within the money you're willing to pay.
Enjoy the journey!
For more richness, you might look at Conrad Johnson gear. The MV-50/52 etc. for instance might be just the ticket for you, and save you some money too versus some of the other suggestions above. You need to be a little careful with the Audible Illusions, since it has relatively high output impedence. You should look for a power amp with higher input impedence. Also, you may be disappointed with the bass you get from your tube amp transition compared to the Classe. Everything's a trade-off, and you need to decide what matters most to you within the money you're willing to pay.
Enjoy the journey!