Cartridge or Pre Amp

Your AT-ML150 is a great cartridge! Do not change it to MC or whatever MM, it will be the biggest mistake. The AT-ML150 has gold plated Beryllium Cantilever and Micro Line stylus. Beryllium is not available anymore from any manufacturers. MicroLine stylus is one of the best stylus ever made! You have absolutely amazing cartridge and it’s hard to beat by MC or MM, only if you will upgrade to AT-ML170 or AT-ML180.

The weak point is your TUBE phono stage, look for JLTi phono stage made in Australia, because some nice NOS tubes will cost you as much as the new phono stage (lol). Personally i would avoid cheap tube phono stages.  

JLTi + AT-ML150 is a killer combination, it is possible to change the loading up to 100k Ohm (instead of 47k Ohm) if you will ask Joe to made a free mods to his phono stage, he could replace internal resistors to 500k Ohm, after this mod JLTi is the most flexible phono stage with RCA plug load resistors on the back. MM or MC can be loaded to whatever value.

I can only laugh at $30k equipment and the marketing strategy related to this business. 

Maybe you’re right, but based on my experience it’s hard to motivate a person to jump from $300 product to $3000 product.

The JLTi is not cheap sounding phono stage, if you know who was Allen Wright, who designed JLTi with Joe, and if you will look at the price tag for the first 3 Wright’s versions you will notice they are over $2k. New version does not have that fancy design, but amzing for the money, now $750 (AU$990) including shipping (extrenal power supply is optional upgrade).

Luckily there is NO tubes at all, which is a limited factor in my opinion !

For MM cartridges the JLTi is one of the best phono stage on the market at very reasonable price, no other phono stage alows the user to change the loading for MM cartridges.

@bpoletti the Herron is $3650 and it must be very good at this price, but the OP using $399 Pro-ject tube phono. The JLTi cost $750 including shipping worldwide and it's much cheaper than previous $2k version. 

@joysofsound The AT-ML150 OCC or modern AT150MLX ? 
Anyway, both are very good MM cartridges, no worries, but the AT-ML150 is better. 

Upgrading your cheap tube phono stage is what you need. 
The JLTi is the best for both MM or MC for reasonable price and the latest version is much cheaper than previous swiss version, but the performance is even better.  

   

The AT-ML150 is great, i've tried all cartridges from this series, for $350 the AT-ML150 is unbeatable! The sound is full of details, for double price the AT-ML170 is better. I've tried these carts with different phono stages from $500 to $2500, it wasn't dark at all. Zu Audio Mission Phono cable is great and you can buy one directly from zu audio promo auctions on ebay under $150. 

I may also experiment with upgrading the stylus.

Replacement styli for AT-ML series are impossible to find nowadays, they are expensive. New styli for different AT models are not compatible and not as good at the ATN170 or ATN180 styli you may want to upgrade for. I think you have very little chance to find a better AT stylus than your beryllium/linecontact ATN150, this is how it looks under my macro lens. Beryllium cantilever with pressure fitted nude LineContact diamond. Beryllium cantilevers are no longer available in the industry. If you can’t hear the potential of this AT cartridge, then something wrong with your phono stage, maybe you need a top quality NOS Telefunken military tubes to improve the top end and clarity. I;ve bought all the best NOS tubes to experiment with my amps, but i ended up with First Watt gear and i don’t want to get back to tubes anymore. With MC cartridge like the ART-9 you will have even more problems with phono stage. Like @jollytinker i am a user of ZYX CPP-1 headamp and various SUTs along with different MM/MC phono stages.

If you can’t get the righ sound from such a nice AT cartridge then it’s too early to think about LOMC. The ART-9 is reasonably priced, but the phono stage or sut will cost you twice as much to the cost of the cartridge. When the MM cartridge sounding "dark" i would recomment to change the loading from 47k Ohm to 100k Ohm.

I wish i could find more styli myself as i am using AT-ML180 now (it’s a killer MM cartridge, one of the best ever). If you want to experiement with stylus then you can use that plastic stylus holder frame to send to SoundSmith for Boron Cantilever, i mean this one. If you want to look at comparison chart of the different AT-ML models you will find it here.

LOMC is not panacea in your situation, it will only cause more problems.
Life is easier with MM carts, some of them are exceptionally good compared to expensive LOMC.
And this is why i recommend JLTi MM/MC phono stage with its" diamond transistors", this is how it looks inside: https://scontent-arn2-1.xx.fbcdn.net/v/t1.0-9/18275023_1683323108352516_8614811338337251752_n.jpg?_n... 

@basement 

Generally speaking, where low output MC's put more demands on phono stages that MM's, high output MC's put less demands than both.

In was quite normal to use MM stage for HOMC cartridges, but i never liked the result, actually optimal loading for HOMC is not 47k Ohm to my ears. Also moving mass is always higher with HOMC than with decent MM, so i think there is no advantages of the high output MC compared to some nice MM or MI cartridges. 

hey @invictus005 have you compared Parasound JC3+ to Gold Note PH-10 ?