hiline upgrade. Is it worth?

A Hi Line will be an improvement, and if you decide to stick with Naim sources  it will be worthwhile.  However, many here have moved to Chord dacs as sources - the hiline no longer needed.  The new streamers may change things again (we are a fickle lot).  But for the moment a used Hugo seems a better purchase than a new Hi Line.  If you buy a used Hiline check it carefully for damage; it is extremely fragile.  Fortunately Naim seems to be rather generous with regard to repairs.

 I was surprised by the significant upgrade swapping to a highline brought in my own system .

 If possible, try one in your own system before buying. 

I've used a 5-5 hiline on my digital (CD) side and 4-5 hiline on my analog (TT) side. No doubt I heard a different presentation with each. I considered the 5-5 a positive upgrade on digital, the 4-5 less so. Worth it? All depends on your wallet and what you're expecting to hear from your hi-fi.  @blythe 's advice to try before buying is sound.

I tried a HighlIne on the committee (wife) listening tester years ago. Here's A. Here's B etc. Clear preference heard and the HighLine remained.   

It’s one of the better u-grades for a Naim system. DIN connectors will also work much better than RCA.

Surely it's a nice upgrade and in the future I think I'll always stay in Naim.
The problem is that the dac-v1 is 4 pins and I'm afraid that naim will release a dac-v2 with 5 pins in the future.
Or if I decided to switch to a streamer like nds-2 my hiline 4-5 pin would be unused. and it does not cost a little

A Naim Hiline interconnect RCA-5 Pin would be effective AS a A Naim Hiline interconnect 4 pin to 5 pin?

I think you slightly misunderstood the connectivity.

The primary functionality of a DAC V-1 is to act as a combined pre-amp and a DAC. Hence the classic 4-pin 270 degree output, for connecting directly to power-amps.

DAC V-1 has an additional feaure of acting as a source component - hence the need for a specialised 4-5 DIN, when connecting to one of NAIM’s pre-amps.

Currently I use the dac-v1 only as a dac, leaving the pre section to SN2.
Is the point HILINE 4DIN TO 5 DIN or HILINE RCA to 5pin DIN?
Will there be differences? which one should buy?

HiLine is a nice cable but the design of the collars is a negative- they are just too fragile. 

Other "chord" manufacturers provide Din connectors

ATB,

Mark

Between Dac-V1 and super nait 2 - probably not.

Between ndx and sn2 - most definitely. 

Big bump in sq bewteeen my V1 and 110 with a Witch hat. Might want tp try one of those first. 

For the price of a Hiline, if you're serious about upgrading, considering a renderer, e.g. Sonore microRendu, between your MM and DAC-V1. I currently have one on trial at home. I know there are other renderer options.

Dave