My turn.

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Hello everyone.  I know the subject is probably beaten to death, but it's been a week since I turned my Mainline on for the very first time to listen to the music.  I'm estimating that it has about 80 hours on the timer.  From what I can hear the overall sound got so much better from "new", no doubt!  However I don't expect any drastic changes in the sound from now.  At this point I can honestly tell that the upper mids and the highs are too harsh for my ears. Is there any way to upgrade to better components, to make them smoother?  The famous Auricap High Resolution Polypropylene – 18uF 400V are not available to buy anymore.  Is there something else that I can use/do? is it even with it?
I decided to get this amp to go with my HD800. The music is heavily EQed before even hits my ears, but no matter what I do I cannot get rid of the harshness in the regions mentioned above.
Thank you.

[johnsonad]

I did a quick search and there are 18uF Auricaps available if your heart is set on them.

[ALL212]

The HD800's have a mod...not saying that's what will "fix" this but they are known to have issues.

And what are you feeding the Mainline with?  What source?  What cables? 

I suspect upgrading components in the Mainline might be one solution but there may be an upstream issue to look at first.

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I'm totally aware of the HD800 flaws. I've tried Anaxilus mod and then I've tried Super Dupont Resonator, which I'm using now. I never tried them both at the same time.  I didn't need to because between SDR mod and some eq my HD800 paired up really nicely with another (entry level) tube amp that I own(I'm not gonna mention the name).  That wasn't enough for me and I decided to kick it up a notch and got the Mainline .  All my music is FLAC, WAV or CD and it's going through an audio interface as I'm using the headphones to both mix and enjoy the music(we can argue about that later).  The interconnection cables are just stack(planning to upgrade soon).  The headphone cable is balanced Sennheiser CH800 S(planning to upgrade soon).  That's my chain for now.  I think that if this setup made me happy with the other amp, why wouldn't it happen with this amp?
My heart is not set on Auricaps.  Maybe there are some other choices.  And you're right everything contributes to the sound that's going into your ears.  I'm totally open for other suggestions.
Johnsonad can you share the link, please?         Thank you.

[Alonzo]

If your open to something different, Jupiter HT Flat Stack 15uF's are great.

[JamieMcC]

Just wondered what dac you are using and if was it was saber dac chip based by any chance.

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The source computer is hooked up to Focusrite Saffire pro 40 interface which I believe uses CIRRUS CS4272 AD/DA converters.

[fullheadofnothing]

Have you tried another source?

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No fullheadofnothing. I have not.  That's still to come.  I'm very new to the seen. But I can honestly tell you that I can hear the difference when I bypass the audio interface and connect the amp(s) directly to the computer.   So I believe that the converters in the audio interface do something.

[ALL212]

While bumping around the threads here in Mainline land I found this.  Not sure if it's true and would be hard to test but are you running the tube shields in place? 

Having the tube shields in place for the 6C45s is also a precaution against radio-frequency pickup in the tubes which could result in high frequency oscillation. 6C45 tube oscillation can make the output of an amp containing this tube sound "hard", or have harsher treble. Best to keep the tube shield in place in my opinion.

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Wow! You live and learn! I can't wait to get home and test the sound without the shields.  I'll report back soon.

[Sugar Man]

If your open to something different, Jupiter HT Flat Stack 15uF's are great.

+1.  Love the Jupiter HT Flat Stacks in my Stereomour II.

[bAd]

Removing the tube shields didn't make any difference for me.
 I don't think I wanna spend $199 a piece for a pair of capacitors. It's a bit too much.  $200 for a pair is as high I would go. Is there anything else out there around that price?
Thanks.

[Alonzo]

Obbligato Oilers.  Surprisingly good but big, around $20 a piece.  M-Cap Supreme, around $50 -70 each.  There are others but these have sounded the best to me at the price you want to be around.

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M-cap supreme sounds good, but to be honest with you all I need some more information about the parts. Like which one to choose e.g.. ??uF  VDC. I have no idea what I'm dealing with here meaning, that I'm just so fresh to the game you have no idea.  I've never solder anything in my life until a couple months ago, when the Mainline kit arrived. I know.LOL. Please be patient with me.