Analog upgrade path

There's no right or wrong, it all depends on what you want to do and when. You'll hear a lot more improvement from a good phono stage like Herron VTPH2A with your current table than you will ever get from a VPI or anything else with a budget stage. 

But if you would be able to audition phono stages (unlikely) then it could still make sense to do the table first, because then you would have a much better idea what you're comparing. That is the order I did it in, great table/arm/cart then phono stage hunt. But that was back when thought home auditions were essential and was willing to do the work getting a dozen (seriously) different phono stages into my room.  

Nowadays I would just say below $5k there's the Herron, and the Decware, pick one and never look back.  

Either of those are good enough to be end game for a lot of guys.

Don't forget, whatever you get, the difference between whatever it is sitting on some rack vs properly optioned out on a massive shelf with Pods is the difference between a $5k front end that sounds like a $5k front end, and one that sounds like a $25k front end.

How were you playing your TT with your Integrated Amp?

What cartridge now?

As far as TT, if no problem with that one, in your budget, I say stick with the TT.

Phono Stage: MM only or MM and MC? Tubes or SS?

IMO, any phono stage needs to be purchased with return option.

How are your cartridge alignment skills? 

If your turntable is in good condition then I think you need a great cartridge and phono stage first, you can upgrade turntable later. 

I'll agree with chakster. Get that PH5, then a cartridge and down the line a suspended turntable. 

The integrated amp I have been using is an old Vector Research with onboard MM/MC stage. I’ve sourced an ARC LS25 mkii, as well as a Legacy power amp which is essentially a rebranded CODA Stage 3.3. Both of these pieces are sitting in their factory boxes until I can get together an appropriate front end to pair them with.

The Technics is in very good shape, although fitted with a very basic AT-3600l cart.

Start with a better cartridge. A Hana SL ($750) is a good choice! The phono stage in the Vector is perfectly capable of high quality sound from the Hana mc cartridge. In fact you can use tape out from the Vector into the LS25 II while deciding upon a new phono stage! 

If $750 for the Hana SL is too much, a Hana EL for $500 should be more affordable. I recommended the SL first because its Shibata stylus offers superior performance and longer wear than an elliptical stylus. 

I had a chance to look at my Vector Research, it’s a VA-1400.

Ok, looks like I’ll be hanging tough with the Technics for awhile. 
The Hana SL has some pretty great reviews. Wouldn’t I require a step-up transformer in addition to a phono stage to run that cart, however?

The few references I have discovered on the VA-1400 confirm your description of the presence of both a moving magnet (MM) input and a moving coil (MC) input.  The MC input should be able to support the Hana SL.  Your other option would be a step up transformer (SUT) adding the needed extra amplification and using the MM input.  I would start with the direct MC input and experience the cartridge for a while then decide your next acquisition...  

There are many great moving magnet cartridges better than the Hanas.
In less expensive or older equipment with a lower signal to noise ratio high output cartridges will sound better and avoid the requirement for a more expensive phono stage. Moving coil cartridges do not come into their own until you are spending $4-5K on the cartridge and phono stage.
The high output Soundsmith cartridges match up with any $6000 moving coil setup. Don't let prices fool you. They are to separate markets. The $3000 "The Voice" is just a high output version of the $5000 Sussurro.
They are exactly the same except color and the Voice has a few more turns on its coils which are fixed! I asked Mr Ledermann why they were priced differently and his reply was, "different markets."  When asked why he even made low output cartridges he replied,"because that is what people want, They want to be able to use their expensive phono stages."

I would first upgrade the cartridge to an advanced stylus shape.

https://www.sound-smith.com/articles/stylus-shape-information

If you play it (MM or MC) thru your VA 1400 first, you will hear only the improved cartridge. 

Then, to use your two nice pieces, you need to get a phono stage as you know. I would go for one with inputs for two tonearms, MM input and MC input with options to accommodate your new cartridge and future new MC cartridges with different signal strengths and coil impedances.

You will definitely have a much nicer sounding system,

Well, this seems to be escalating quickly...
That Soundsmith Voice cartridge is well outside my budget. The article on stylus shape was certainly informative, however.
$4-5k was my (now very much blown) original budget for getting a complete system up and running lol.

Oh, my power amp’s s/n is 92.5db, since that was mentioned.

Any thoughts on the Goldring 2500? I’d been looking at that cart previously.

goldring.. 1042 is excellent mm cart. and it's cheap. 

It can do alot of things and alot to like for the price. hard to do any better below 1000 usd

I saw it trounce a high price Mc before

it's one of those cart that makes music sound like it supposed as intended. not too much not too little. I highly recommend it

basically kick nagaoka mp 500 out of the park too and some others. many upset people lol

It can do alot of things and alot to like for the price. hard to do any better below 1000 usd

Why do you trust people who never owned good MM cartridges ?

You’d better ask for a list of cartridges from the owners of Goldring before they will tell you this is the best.

Some people don’t even know about better cartridges, they never heard about Garrott Brothers, because they are British or Americans, but it’s Australian cartridge. I have never ever read from anyone about direct comparison of Garrott Dynamic Coil cartridges to mainstream like Nagaoka, Goldring or whatever.

However, cartridges that kills many of those overpriced LOMC are not new MM/MI, but vintage MM from the golden age of MM design (70s/80s). Those are unique in many aspects of design.

BTW Nagaoka is very old design, in Japan this company called Jeweltone and all those PM-100,200,300,500 designed in the 70's and sold in Japan under Jeweltone brand models MP-10,20,30,50 (Nagaoka is only export name for same cartridges). 

@chakster of course there are always something better for someone. 

for the current mainstream easy to get  stuff. 1042 is very worth it. we call it a value studio cartridge. it's neutrality is uncanny. 

like listening to say Genelec... rock is rock. love song is love song. live music u feel the heat.. that kind of cart... 

300 to 400 usd in ebay.. stylus 250ish. reasonable 

@anthonya I read on another site that the 1042 has a very close sound to the 2500 at a lower price point, as well as being amenable to a wider variety of tonearms.

@chakster I read a previous post of yours regarding the Garrot brothers. A very storied history with a rather tragic end.

I came across an 11 cartridge shootout on another site 

http://soundadvicevinyl.com/2017/12/04/under-1000-moving-magnet-cartridge-shootout-11-cartridge-reviewed/

the winner was The Vessel r3sm. What caught my attention was that the cartridges were all evaluated on a Technics ‘table, which makes me think this might be a good match.

I will say that I’m really picking up (no pun intended) the difference a cardridge can make. I have on hand a Technics SL-2000 I bought as a gift for my younger brother. It’s fitted with a Shure m93e, and I can say that I certainly prefer the AT-3600l on my ‘table.

Not sure about your budget, but check out the Tavish Audio Design "Adagio", Modwright "PH 9.0" for tube designs or the PS Audio "Stellar" and Gold Note "PH-10" for SS. At least the first three offer trial periods.

@grk my budget started out at $500, then I thought maybe $1000 was more in the proper range, now it’s looking like $1500 is my absolute upper limit and giving me an ulcer thinking about it. What can I say? I’m a proletarian.

I’m actually really interested in the Decware Zen Triode ZP3, since millercarbon was kind enough to alert me to it’s existence. Great review in Toneaudio issue 74. Seems like a very reasonable price considering what you get, and I like that it includes the option to later add an SUT with adjustable loading if I decide to take the plunge and move to a MC cart.

Cartridges wear out.

Turntables don't. Neither do tonearms. Nor phono stages. Anyway, investing in any of them will get you further than a cartridge, even a Koetsu (which I own). IMO.

I had a Technics SL1500 in my room for a time, paired to an air bearing tonearm and a good cartridge. Didn't care for the sound compared to my belt drive tables.

Since you are considering staying with the SL1500, you are obviously content with a non-suspended table. In that case, an air bearing arm may work best for you, and yes, one of them is affordable.

I use two air bearing tonearms from Trans-Fi, the Terminator (don't blame me, I didn't name it). At about $1200, the best buy in high end audio, but won't work on a suspended table. That's where I'd go: (1) Terminator, (2) belt drive unsuspended table (3) phono stage. Save what you didn't spend on cabling to get a decent cartridge, and when you've got lots more to spend, upgrade the cartridge.

That way you spend money on non-depreciating assets instead of putting money into a depreciating asset and getting less bang for the buck (a cartridge). IMO.

I know almost nothing about cartridges but I do know that Goldring 1042 sounds quite good with Nottingham Spacedeck/Spacearm and Acoustech PH-1 phono stage. I am sure there are better MM cartridges, both vintage and modern, but for the price new it would be hard to beat, maybe some AT on sale. I got mine from the UK, analogueseduction.net
Cheap budget phono is never a good idea. In your case, I would upgrade phono stage and maybe cartridge first. But if you wanted to upgrade everything step by step then yes, I would probably start with the turntable. Depends on how much to spend and when. Or maybe wait longer and then upgrade everything at once. That's what I did.

The link will show you a few recent responses from MK1 users.
Reply 11 is worthy of consideration.

https://www.lencoheaven.net/forum/index.php?topic=31031.0

I personally own Vintage TT's and like to think that a overhaul with a modern thought for available materials works in favour of the Performance to become on offer.

When choosing a TT to be used as the Main TT on the System,
I would have electrics circuits assessed by a competent person and the Circuits Boards / Components thoroughly cleaned.

The Platter Spindle Bearing would be next on the List to be Investigated.
Using gentle finger applied pressure to the Spindle Checking for any sensation of a Spindle showing it is allowing a Side Ways Movement.
If a  Vintage TT is with a unknown History, or known and a exchange of a Bearing Housing Bush is not believed to be needed,
learning how to remove and flush the insitu Bearing Housing Oil will be the next on the List.
Followed by learning the Oils available today that will be the best to be used as a the New Oil. ( There are Oils Today designed to work at their optimum in a setting that is very similar to a TT's Spindle Bearing Housing, especially with modern additives that allow for a decreased friction and Drag on lubricated parts.)

Looking at the underside of the Chassis in the Link above, it looks like it the Chassis can have a Underside Treatment Applied of a application of Modellers Clay such as Newplast ( Reversible) or,
a Bituthene Tape ( Residuals would be left if Reversed).
( This as a Chassis Treatment is cheap to achieve,
it can be investigated to decide if there seems to be a merit to be achieved in carrying out the Treatment )

Again using the info in the image in the Link above, it seems that there is a opportunity to use a Independent Disc for the Tonearm Mounting Base.
(There are a large selection of materials that could be trialled as a substitute for the Original)

The same is looking like it can be said for a Tonearm Selection as well, if the Tonearm Base is exchangeable.
(As the slight variations of a Tonearms Geometry Set Up needs can be catered for in a Bespoke Produced Tonearm Base ).

In my View when much of the above is achieved ( not too difficult )
a well thought out Investigation into Mounting the TT will be very worthwhile as a undertaking.
Selecting a Rack Shelve Material and Footer or Wall Mount Shelve Material and Footers, will effect a presentation from a TT,
in cases exchanges of either Shelve, Sub Plinth Materials or a different Footer Design can produce a very desirable presentation.
Shelves and Sub Plinth Materials and Footer Types when carefully  selected for a TT really be a beneficial time taken to assess and select.

When all the above is in place, i.e TT > Tonearm > Cartridge >
TT Mounting.
The how to get the best from the Set Up,
by trying New Types of Electronic Devices in the System will be quite revelatory in what can be learned of a devices contribution.

Have a few different Platter Mat Materials to use as well,
( Loan some if possible )
I have auditioned Devices in the past that were underwhelming, and not comparing in a desirable perception to other used devices.
When a Platter Mat was exchanged the performance was vastly improved, and much wanted. 
I have Leather, Felt, Foam, Rubber, Ceramic and Gunmetal.
The effects can range from Bloomed > Richness > Perceived Weight >
Lean. 
I have used a few of the above practices beyond my system,
by taking My chosen Sub Plinth > Footers and Platter Mats to other Homes and used them on other owned TT's.
The response from a TT owner is sometimes Jaw Dropping as the results of the exchanges are so noticeable. 
I don't encourage a presentation type, this a individuals unique choice,
I enjoy helping the person get closer to their wish list.

Well there are a few Two Cents Worth snippets of how I use some of my 'Spare Time' around preparing my owned Vintage TT's for a life at the front of the System.       

I would dump the turntable. Buy a pro-ject classic evo and a hana el cartridge (crazy good for $475) or both the goldring eroica lx and Denon 103. Alternatively, buy a Music Hall mmf-7.3 with pre-installed ortofon 2m bronze. Then grab a pro-ject tube box ds2, a killer tube stage for a grand...go look at the reviews. It slays stuff costing much more and has all the adjustments you would ever need. Lastly, buy an apollo turntable shelf, built like a tank in the UK. If you want to throw money away on a 5k phono stage, go right ahead....there are plenty of phono stages available for a grand that are fantastic. Another would be the Tavish classic @ $699. Even the tavish adagio is only $2500.
I speak from actual experience, as I own all the above, with exception of the adagio. You will need to spend 10k or far more to get significantly better analog sound. One last thing I forgot to mention, I would highly recommend the Jensen Mc 2rr step up transformer for the both the Hana el and Denon 103 cartridges. It is an amazing SUT for $599. The Jensen has a built in load of 430 ohms, perfect for both cartridges. Also, use dedicated low capacitance short run phono cables such as those made by Atlas cables or Rothwell. I use .5 meter lengths.

You don't say what cartridge you are using.
It isn't a good idea to upgrade turntable and skimp on the phono amp.
Getting a nice phono stage will certainly be the single best sound quality for money move for you now..

I have had many ARC pieces; until last year I had run an LS5 with a PH2 - both fully balanced.  This lasted me for trouble-free years 25 years and I liked the ARC flavoured sound.

I have upgraded to a Ref 6.  After a two month loan, I went with the van den Hul Grail SB.  It may be outside your budget but IMO it is a good bit better than the top-end ARC and a lot better than Boulder 508.  Overall this upgrade has transformed SQ by a quantum leap. 

figuring what goes well with what is what makes this hobby fun as well. many roads leads to rome. a skilled knows how to make a cheap system work and otherwise a poor player can make expensive gear sound awful. 

having a good turntable which allows good vta vtf adjustments, low noise and rumble. i think that goes before investing a more better cart that not only suites the setup. 

eg. audio technica is more thin sounding
. it sounds better with idler type of tt. nagaoka will work well with dd. well nothing written in stone but leave budget for experiment