I mainly use izotope limiter for limiting, Sonnox Inflator and TransMod ( very very subtly ) , variety of EQ's, usually Kirchoff EQ.
For Compressors: SSL BUS or Shadow Hills or Elysia.
Sometimes UAD studer tape.
and other plugins depending on the song.

I saved up a bit to get a hardware unit, but deciding which hardware unit would really be beneficial for me, an EQ, Compressor or some enhancer or some something. Something that none of the plugin can emulate. If money wouldn't be an issue I would get Fairchild 670 of course, but thats way out of me budget, I'm thinking something under $3,000 USD

Honestly just save your money. Maybe rent something to see if you like it?

You could probably get an SSL Fusion or one of those Tegeler units in your price range. Try one out to get a feel for the added work and hassle involved in printing every master thru it and see if the difference in fidelity is worth it to you.

Personally, and I have done this experiment, I found it wasn't worth it. One or two pieces of midrange hardware isn't better than good plugins. Its more work for questionable improvements but still lacks the eye candy appeal of stacked racks that might appeal to some clients on socials.

Don't get me wrong, I love hardware! But just save up until you can get the thing(s) you REALLY WANT to make the process worthwhile, don't just blow 3 grand on 'the best thing you can afford' ...it ain't worth it!

ymmv

Try some stuff on access analog to see if you think it’s worth it

It depends a little if you are doing it for yourself or for clients. On your own material you can probably work without hardware. You do ideally want what you perceive to be the best when working professionally. Many mastering engineers work with a just a few selected pieces of hardware or these days just software.

To complicate it ME's that use a lot of hardware will suggest there is great interaction between multiple devices, impedance loading (arguably a fault in modern times), and multiple coloured devices. That's fun and I am sure covetted deeply as something very special.

However ultimately the only thing that matters is the end result, nothing else.

Not all mastering rooms are stacked with $40K of hardware choices. Starting out today that would be probably be a poor choice unless you are already very well off financially.

There is some equipment that is not emulated well enough though at this time in my opinion.
Some emulation is very poor indeed.

Clean equipment is pretty much done and dusted. So close it would be barely distinguishable and 100pct indistinguishable and probably rejected in a master that was only slightly subjectively worse (settings of the devices themselves) in comparison to something in the box only. And that includes much compression, as mastering engineers are rarely tucking in with 3-12dB gain reduction. Compression as we know is generally minimal, even a free digital compressor set up correctly won't get too ugly with 0.5 - 1dB gain reduction.

Unfortunately $3,000 falls short of most hardware mastering processing equipment. You will probably get more for your money second hand if you live in the US though.

What monitors are you using ? That was not mentioned, they are a big deal for 99.5pct of audio engineers, especially mastering. Maybe get $3,000 of monitoring if you do not have that already (room and monitors, you can do the acoustics for a low price if you DIY) This way you will judge what is already there more accurately (supremely important) and any moves with software will be better judged.

That would be valuable.

no one can tell you what gear you might consider being worth buying...

...and then there's the question whether analog hardware has any advantage over digital hardware or software?!

imo not at all (which is why i have sold all my analog hardware, except for a few channel strips which i'm occasionally using for recording/mixing).

I mostly master for myself but once in a while others ask me to mix and master their recordings.
My monitors are: Genelec 8040 and Yamaha NS10m. ( and bunch of headphones )
upgrading monitors is something that is on my to-get list when I'll save up enough ( or get a loan or credit ) in $5,000-$15,000 range,

Hey! 100% DO NOT buy any equipment on load / credit when you're starting out and only have a limited client base. (Sorry to text yell but that stresses me right out, and f*** the banks)

Only invest once you know that there's enough work coming in to justify the purchase. Or once you save up enough disposable income and feel like treating yourself. Also perhaps consider what benefit there is to analog processing that you're actually, definitively, unable to accomplish digitally. I'd argue in 2025 there isn't much aside from the fun-factor.

That said I love my analog equipment and use it daily. But at this point its very much not a necessity, just a luxury that (usually) I enjoy using and that (initially) helps me work faster.

But you could look at it a different way. You have $3k you could use to develop your business / side hustle.

yea I think I should get high-end monitors first, the ones I have are very good but not great. monitors are the only thing I'm lacking. doing all sorts of audio and music work for past 20 years or so I really learned to listen, mix and master, so a high definition, flat monitors that also extend well below 55hz is what I need

Can't recommend the Vertigo VSC-3 enough for compression.

I would focus on monitoring and conversion first. There are lots of amazing analog boxes but I’d address that at the end of the journey and nail your monitoring first, and then factoring in conversion as you think about outboard processing. Those analog boxes will always be there when you’re ready. But if you get your monitoring nailed so there are no questions about translation, and ensure your conversion will get the best out of your analog path, you’ll end up happier in the end and not chasing your tail. Please believe.

Totally agree with the post above.
I would add this : plugins now are very efficient for compression tasks. That being said , no plug-in can emulate the magic behind the tubes. Tubes in general are sonically very complex , hard to emulate. Plug-in can sometimes replicate some 2/3 harmonics orders but there is much more behind the tubes...
in conclusion I would invest in a tube stereo hardware comp or EQ because tubes have a sound. The rest can be achieve digital.
Just my opinion.

Yeah man. My point is that none of the magic of hardware really matters if you can’t accurately hear from 20hz to 20khz. I would make sure I can hear so that I can really know what all of those nice tubes are actually doing to the audio across the range. If I had $15k and had a room, I’d spend almost all of it on monitoring and start listening to references. Then I’d get outboard, and tube goodness. It’s not the cool sexy answer. But…. IMO. YMMV.

I'm no pro, but if i could only keep one of my HW units, it would be the HE2 from Cranborne. It covers a lot of ground in the tone-shaping domain with just a few controls, then I'd do my surgical stuff ITB.
I don't know if there is any SW that can match it or not... maybe?
It's not that expensive.

Monitoring (acoustics are part of that) first and foremost! And never pull out a loan...

Once the playback side is really taken care of, you will also much better be able to judge what hardware outboard is doing for your end results. I feel that a high end compressor cannot be surpassed by emulation when it comes to plasticity, depth and groove, so after monitoring that is where I would look first.

(For monitoring I went with calibrated Dutch & Dutch 8c's. Never had to look back since I bought them in 2018.)

Like other posters, maybe a sub and some acoustic treatment.

Do you already have nice converters to run outboard through?

I don’t think the OP is trying to start a mastering business—he probably just want to master his own tracks. If that’s the case, the focus should be kept simple: use plugins to increase loudness without compromising sound quality. That’s really the core of it.

If you’re mixing and mastering your own music, it’s important to drop the mindset of “fixing things in mastering.” That approach doesn’t really hold up. As obvious as it sounds, you should always aim to solve problems as early as possible in the chain—meaning, get things right in the mix rather than relying on mastering as a band-aid.