Re: jsx combo or vypyr 75
I don't have any experience with the Vypyr but I've played the JSX a lot and it's a great amp at all volume levels. That being said, you're really talking apples to oranges here. The JSX is not going to have the effects and direct recording options that the Vypyr will give you. Still, the JSX, IMO, is more expensive for a reason, it is a superior amp. If you're looking for all the bells and whistles in a strictly bedroom environment, the Vypyr or something from Vox and Line6 will suit you. If you want a great amp in any situation, loud or not so loud, the JSX will give better tone - you'll just have to get something else for additional effects beyond distortion and reverb.
Not knowing your budget, I'd go with the JSX hands down but if cost is a concern, I'd also look at something like the Blackstar HT-5. I don't use a lot of effects or a heavily processed signal and I find the budget priced modelling, effect-laden amps to be less than stellar.