My first amp was a Fender Princeton Reverb, fast forward to various tubed Champs and a Twin Reverb, a Vox, and a Blackstar, I know what a tube amp sounds like.
Tube pre-amps are the way to go with computers and multi-effects.
I plug my acoustic, classical, and electric guitars into tube pre-amps and then to the input of a Line6 POD HD Pro X, plus I use a stereo pre-amp in the effects loop and insert it where it's needed, then that's plugged into a USB interface and powered speakers.
Nothing else sounds good to me via a computer, nothing.
With the tube pre-amps and the POD, I've got *complete* control over my tone and there's nothing lacking with the tube preamps to color the sound, but the POD sounds like krap without the tube preamps.
That setup is easy to transport with a laptop/4-space flight case (power supply, pod, and stereo preamp takes up 4 spaces, laptop secured and covered), much better than lugging around tube amps. It's heavy, but not a back breaker. I won't buy another tube amp and will continue to refine my sound by tube pre-amps, signal proseccors, and computers and computer mixers and computer interfaces.
You need a real good computer so don't skimp on the computer, but you can skimp on the preamps and multi-effects and get a complete setup cheap if you know how to use compressors and noise gates and other tools to refine sound. I use a circa 2012 workhorse, a Dell Latitude with an i5, 16-gigs of ram, ssd hd, Win 7, military grade casing (it can be thrown and it still works), does everything I need without a hitch after getting everything synced. Cheap computers will leave you frustrated because cheap computers can't reproduce true high definition sound and that's what makes the difference, a good computer. This Dell does full high def with a Focusrite 2i2 2nd gen into Reaper with the proper configuration.
Oh, and here's the kicker; be ready to invest big money in cables. You need to go full Mogami or better or stay home, you'll sound like krap if you use cheap cables. And, the cables I use with a multi-input stereo rig costs 5 times more than my laptop! I got this laptop cheap refurbished w/ an ssd, the cables are over 1k dollars, the laptop 300. ...XLR cables, patch cables, guitar cable, wireless connection to pedal board, non-wired to pedal board, two pre-amps with seprate outputs for acoustic and electric, it ads up quick, over 1k for cables.
I started out with junk and worked my way up over the years, so don't let all that get in your way, just eat the elephant one bite at a time, get what you can but focus on a good computer first, then a good signal processor, then good tube preamps, then good cables. You can start out for about $500.00 with an older Dell and an older USB interace, ok cables, almost any multi-effects will do the trick but the ultra noisy ones like the Fender Mustang Head I tried. A Behringer pre-amp can be gotten cheap and get the job done better than an any amp head I've tried thus far...Blackstar, Marshall, Vox, Fender, none sound as good as the above.
Otherwiwse, it's about 4k for the ultimate budget computer studio quality rig (not including the gutiars unless you use a cheap guitar you can play the krap out of, lol), and it's a rig you can take anywhere if you have a TSA case.
When I upgrade the cables, USB, laptop, and Line 6, if I ever upgrade, I've already shopped it out, the next level of good, we're talkin about, oh, at least 10 to 20k for ultra high quality equipment. No sense putting junk cables on a 2,500 dollar multi-effects/amp processor and a 1,200 dollar high quality laptop and a 500 dollar interface ,right? ...at that point, the cables collectlvely cost as much or more than the computer and effects and interface!
It will be interesting to hear how a cheap multi-effects sounds through a dream rig. I haven't put a cheap effects pedal through the rest of this rig, yet. Should be interesting. The one that sounded the best and felt like a tube amp without a tube pre-amp was a Vox multi-effects I had, it just sounded and felt so natural, but it was very limited in the effects and metal sounds and it still didn't sound good without real tubes, so I ditched it, now I want it back to hear how it sounds through tube preamps I've got now, it should sound utterly amazing!