Connect 78 rpm turntable to Vinnie Rossi L2i SE amp?

With 78s, the biggest factor is stylus size. You need a 2.5 or 3 mil stylus. There are a lot of options, but the easiest off-the-shelf solution these days is this:

https://www.audio-technica.com/en-us/at-vm95sp

Dual turntables are OK, but I wasn’t much of a fan when I had one. You’re better off with something direct drive like an Audio-Technica LP120 or the Technics 1200 mk 7. The best 78 tables made are the Technics SP-15s or SP-10 mk3 / SP-10R.

Phono stages built into turntables are absolute hot garbage. Don't use them.

EQ curves are another thing that most ’vinyl’ people don’t understand when it comes to 78s. Complicated to say the least, also somewhat difficult to ascertain for the older stuff. A lot of the ’book’ values are plain wrong and need to be carefully tuned by ear.

https://plugins.audacityteam.org/additional-resources/eq-curves/playback-equalization-for-78-rpm-shellacs-and-early-33-lps

The most accessible off-the-shelf solution is the Parks Puffin preamp. Almost every conventional suggestion I’ve seen over the years for 78 preamps tends to be nowhere near audiophile-quality due to a bunch of crap in the signal chain, cheap build. For true archival quality, you need both adjustible turnover and rolloff curves, not just a few cherry-picked approximate options. The best off-the-shelf EQ unit is the TImestep T-03EQ made by Dave Cawley in the UK (MSRP ~$3k).

If you’re running it through an RIAA preamp, you may need to reverse-engineer it on the back end to fit the correct EQ curve. The treble may or may not be underrecorded, and the bass may be too high. Depends on the record. Generally, too, some high-output 78 cartridges will not be a good match for higher-end preamps which are geared toward moving coil cartridges. You need to check the specs of everything to ensure you’re not clipping the living hell out of the preamp. You only make that mistake once.

If this is too overwhelming (this is just barely scratching the surface), consider hiring a professional to do it correctly.
https://www.arsc-audio.org/pdf/directory.pdf

Here is a link to a sizable online library of 78 recordings.

Perhaps your wife can find/listen to some of the recordings there. 

I did not try the search function (just listened to a few), but assume that it works.

If the 78's are early on through the 50's there really isn't a simple way the achieve "good" sonics from them @ home without addressing the phono preamp and the various EQ's used (along with the TT/cartridge).

https://archive.org/details/georgeblood

DeKay

Thank you all for your excellent advice. As a first step, we're going to buy something cheap just to be able to listen to what's on the recordings -- some are unlabelled, some are even home recordings from a family of musicians, and my wife just wants to see what's there, and to know what's worth sending to a pro for digitizing for the film.  Later we'll decide if we want a better setup to play through our audio system, in which case I'll start with your advice.  Much appreciated!