USB - SPDIF converter or DAC with USB 2?

Just want to get some other input on this.  I am looking to get a DAC that can support hi-rez files.  I am looking for at least 24 bit, 192 khz for this moment.  I am using a Maverick Audio Tube 1 DAC now which only support 16/44.1 for USB, 24/96 for coax.

I boiled down to 2 paths: 

1) buy a USB-SPDIF converter and keep the Maverick for now.

The advantage is that it provides greater flexibility as I can upgrade the DAC later without the restriction to support USB 2.0.  It seems there are many great DAC out there that only support 24/192 over coax.

I boiled down to the following choices considering the prices:

a) M2Tech hiface

This seems to be the first device doing this.  it has some good reviews, but my concern is that the technology is old and there are new and better things out there now.

b) Musiland Monitor 01 US

This seems to be ok based on other people's review.  It is cheap ($65 on eBay) However, it seems there are some doubt on is it really doing the thing right.  It only works for Windows.  And I also have some doubt in this company.  Some people also have problems with the driver

c) Mhdt USB bridge

This seems promising.  MHDT seems to be a reliable company, and their DAC has very good reviews.  I read the manual, it has detail step by step instruction including configuring the computer and player.  it seems the driver is well implemented and tested.  In short, I have a good confidence in them.  However, this is relatively new and I can't find any review on this.

2) buy a dedicated DAC that can support 24/192 USB

The advantage is that it is simpler, 1 device, and I can enjoy hi-rez music now.  The disadvantage is that the choice is seriously limited with the price into consideration.  I only have 1 choice, which is the Firestone ILTW.  It seems to be a very good deal, for under $400, you get a DAC support 24/192 with good chip.

There are a couple things I don't like:

- It has only 1 USB input

- The current driver doesn't support win 64 bit

- i am not sure about how it sound.  I lost the flexibility as in path 1. 

What is your opinion?  Path 1 or path 2?  If path 1, which USB-SPDIF converter would you recommend?

thanks for the suggestion about the audiophileo and audiogd.  The audiophileo are more expensive at $500.  The Audiogd can only take 24/96.  I am not ruling them out ... but I don't see a clear winner yet.

And Currawong, that's a very interesting comment.  I know the Maverick is a low end product.  So, that's one of the reason I am looking for USB-SPDIF converter which allows me to upgrade the DAC later.  And theoreatically, if the source is improved, the sound is improved regardless of high end or low end product, but whether it is audible is a different question though.

A different quesiton, what is your suggestion in order to hear the improvement of the hi-rez files?  I am open to all comments.

Actually, it is a long story.  I don't use headphone but speakers, and I just upgraded my speakers, preamp and amp.  Then I am tempted to try vinyl that many audiophile preferred.  But I think it is too inconvenient.  Plus I need to buy the turn table, a phono stage, and some vinyl disc, the investment is not small.  And I read several articles where the reviewers think the high rez digital files are as good as analog.  So, I decided to upgrade my DAC to try out some high rez files.  I think this is more like the future.  This is where I am coming from, and DAC is sort of my last thing to upgrade for this round. 

I sort of know or feel that upgrading the DAC may not have any major audible improvement, but just want to try out.  Because before switching to computer and DAC, I use a medium grade SACD player.  And to be honest, I can't hear any difference compared to a normal Sony DVD player.  So, I am not a strong believer in spending thousands of dollars on a CD player.  I know there are many people think otherwise.  Maybe my system at that time is not revealing enough for me to hear the difference, who knows.   

Yes, exactly.  Since I don't want to spend too much on DAC, my target budget is less around $699.  Actually, I can find 2 around my budget.  The Firestone ILTW and Musiland MD30.  But somehow, I don't have much confident in Musiland. 

So, it seems the USB-SPDIF is a better path to take.

After doing some more research and analyzing feedbacks from others, my decision has changed.

I read the manual of M2Tech, and it says the output is higher than usual.  During my course of upgrading, I found out system synergy is a key.  Buying the USB-SPDIF converter add another component that may not be a good match with the DAC ... so, I think buying a single unit is better even though losing the flexibility.

And based on the feedbacks, and I agreed, that 24/192 is not that important.  So, if I change my requirement to have USB support with 24/96, then it opens up more choices.  Actually, there are too many choices.

I am quite interested in the Audio Gd NFB-3.  It is within my budget, and it has good review.  The USB receiver chip also has pretty good feedback from users.  In particular, one of the reviewer directly compared it to the Maverick D1, and he said it is in a different league in every aspect.  However, it doesn't mentioned anything about removing jitter.  Is jitter removal important?  I am wondering how it would compared to the Firestone ILTW.  I know no one can answer this question without A/B testing, but what are your gut feelings?