Depends on where the motor is - in the hood? or located externally?

If you have an internal blower then there's not much to do, I think except run it at a lower speed but as you say, then you're not getting the venting you want.

I'm assuming you have adequate makeup air so that your current hood is operating at its most efficient. If not please read up on that - with adding in MUA you may be able to do a lower setting with good efficacy.

There's always some noise of air moving through the baffles (or mesh, depending on what you have). But two things you can do are get a remote blower and pair that with a silencer, or get a hood with more power than you need, then run it at a lower setting.

I'm not an expert but have learned a lot on this forum - lots of good threads on this topic.

There can be great disparity in sound between hoods pulling the same CFM. In my last kitchen remodel, the sound was unbearably loud and I asked the cabinet maker to swap it out. It was a Zepher, IIRC. He cheerfully brought me a similarly sized Broan and it was far, far quieter. A basic, no frills hood but I love it even more than my previous kitchen’s Vent-a-Hood.

It has been loud since new. It replaced an OTR microwave that had inadequate venting.

I never found a HVAC contractor that wants to look at range hoods. They were all only interested in heating and A/C.

What are some recommended models with remote blowers?

How remote are the blowers? I don't want anything exposed on the exterior beyond what's already there for the roof venting.

That’s strange since venting is integral to all of it. We have a great HVAC company at our vacation house too who did all the vent and MUA work. I guess we’re lucky — two for two on cooperative HVAC guys.

Sometimes I crack open a sliding glass door before using the fan, but it lets in cold or hot air depending on the season.

What other solutions are there for MUA?

Look at Fantech. I installed their double unit in my bathroom (one motor, two intakes; one in the shower, one over the tub). The motor is located in the attic (or can be installed outside on a wall). The bathroom version is practically silent and pulls a great deal of air. I've used it to pull cool air from outside in my upstairs on hot days, after the sun goes down and it cools the whole upstairs! They have kitchen exhaust systems. I love Fantech. https://www.fantech.net/support/frequently-asked-questions/kitchen-ventilation/

You mention in your OP the idea of wider ducting. What diameter duct do you have now? Typically when OTR MWs are the setup from the beginning, the duct installed at the time is 6” or less. If that is the case with yours, your hood will be noisy regardless of brand.

Up North (vacation home) I wanted a 48” gas range so multiple cooks could have fun making meals. The BTUs required 1200 CFM range hood. The range wall is on one side of a stairway and the Rumford fireplace on the other side. We had to install a large MUA unit in the basement to send heated fresh air up though a vent under the range (it has feet). Works very well and the fireplace can be going at the same time.

Example: https://www.fantech.net/our-solutions/kitchen/makeup-air-systems/

I have no idea of the size of the ducting. i just guessed that maybe a larger diameter duct may help.

If so, maybe just gettng new ductwork alone is all i need and I can keep the existing range hood for several more years.

However, if I’m paying for removal and reinstallation of the range hood anyway so ductwork can be done, I might as well get a new hood at the same time.

I just remembered I ordered a backdraft damper years sgo and looked up the receipt.

It was 7 inches.

Is that small? What is the best diameter?

The questions here are too general to answer specifically, or have been answered in various searchable threads here. MUA is required to replace air moved outside by the hood system. No air is moved outside that isn't replaced. Opening doors and windows is partially effective, depending on the case, but for cold weather isn't recommended. Instead, heated air supplied through a path that includes a heater and filter (at a minimum) and which may also require a blower is appropriate. The goal is to keep the household air pressure equal to the exterior air pressure. Drops in pressure not only gag the hood blower, but may cause back-drafting of combustion appliances taking air from the same household volume.

The appropriate size of a duct depends on the CFM being moved through it. What needs to be dealt with here is the cooking surface size, thence hood size and required CFM, then blower specification to achieve that CFM in the presence of pressure losses. Once those are known, the duct size can be recommended and MUA requirements known.

Noise and exhaust performance do not go hand in hand. Vent-a-hood are one of the loudest hoods you can purchase but perform no better than others. A commercial hood performs much better at effluent removal than any consumer hood and yet is much quieter.

There's some more on noise here: https://bamasotan.us/range-exhaust-hood-faq/

Generally the best solution is to have the blower remote from the hood (either in-line duct or external) and place a silencer between the hood and blower. Making sure that hood, duct, silencer and blower are mounted properly w/ perf strap, chain or isolation hangers helps a lot as well.

Do standard (under cabinet mounting) range hoods exist with either remote blowers or very quiet fan motors or would that require a kitchen remodel replacing over range cabinets with one of the chimney-style range hoods?

Typically, undercabinet range hoods are sold with blowers, but this is not either a requirement or a necessity. Reviewing the scope of range hoods in the Wolf Design Guide may reveal which types are available with remote blowers. Other manufacturers' offerings can be similarly investigated.

An undercabinet range hood could be gutted of its blower and a remote blower (roof blower say) could be used at the other end of the duct. Appropriate power cable and control installation would be needed. If space exists, a silencer could be added. Note that the undercabinet hood may well be too small for good performance, but the answer to @jaxo's question is likely to be "both."