[viggen]

During the past few years, I've talked to a few techs.  Two of these techs use mid grade Nichicon caps.  They say they used to use higher end Blackgates and audio grade Nichicons.  But, they claim audio grade caps and mid grade caps only sound different at first.  Eventually, after some time, they sound the same.  Supposedly, the technology advanced so much that even midgrade caps are now considered higher end?  So, they only use midgrade Nichicons now.  It also lowers their cost as they don't stock as many caps.  And, the reliability are the same too. 

What say you?

[FullRangeMan]

I will translate for you>
Years ago a tech that I was emailing used very cheap Epcos caps (TDK owned brand) and said the sound was great and no need more than it, now he is saying the same wonder about another brand he is using now.

Other techs I used in the past also make question to use the brand they were currently having access to, so they don't have to look for another shop and another model from another brand they are not used and doesn't know.

This is the conclusion I have reached having been in audio since the 1970s.

[FullRangeMan]

However in the 2000s I read two articles by technicians saying that Blackgates were the best at that time.  Nowadays I would trust Miflex if there is plenty of funds.
Check this know graphic from Lampizator for reference:

[Speedskater]

That spider web chart displays great imagination. 

Modern capacitors from the major industrial manufactures, made on very expensive machines and checked by large Quality Control departments is the way to go.

[tull skull]

That spider web chart displays great imagination. 

Modern capacitors from the major industrial manufactures, made on very expensive machines and checked by large Quality Control departments is the way to go.

Wouldn't that be Nichicon?

[Speedskater]

Yep, Nichicon would be a modern major industrial manufacture.

[FullRangeMan]

Nichicon corp. is a big company from Kyoto,Japan founded in 1950.
They were made defective capacitos for various years and have not disclosed the origin of the problem to this day.
https://en.wikipedia.org/wiki/Nichicon
Early 2000s capacitor issues
From 2001 to 2004, Nichicon produced defective capacitors ("HM" and "HN" series) that were used by major computer manufacturers, including Dell, Hewlett-Packard, and Apple.[4][5] No explanation has been given for the production runs of defective capacitors, but some sources claimed that these capacitors were either overfilled with electrolyte,[4] or were constructed using electrolyte that was prone to leaking, causing premature failure in any equipment using them.[citation needed] This issue was not related to the Taiwanese capacitor plague.[4]
https://en.wikipedia.org/wiki/Nichicon
In 2010 Dell settled a civil lawsuit concerning its shipment of at least 11.8 million computers from May 2003 to July 2005 that used faulty Nichicon components and were prone to major failure.[6][7]

[FullRangeMan]

Also would also be good buy from a good store like Mouser or Digikey.
Avoid Amazon, Ebay and mainly ALi Express.

Check this stuff about capacitors life spam:
Capacitor type:
Electrolytic capacitors may have a shorter lifespan compared to film or ceramic capacitors, especially in high-temperature or high-frequency applications.

Operating conditions:
High temperatures, voltage and current spikes, and high frequencies can shorten the lifespan of a capacitor.

Installation quality:
Improper installation, with poor soldering or loose terminals, can lead to early failure.

Maintenance:
Regular inspection and replacement of capacitors showing signs of wear or damage can extend the life of the equipment.

Electrolytic capacitors:
These are often used in power supplies, audio circuits, and other applications that require energy storage.

Film capacitors:
They are known for their high reliability and are used in applications such as noise filters and power factor corrections.

Ceramic capacitors:
They are often used in high-frequency applications, such as timing circuits and oscillators.

[FullRangeMan]

Tips for extending the life of capacitors:
Choose the right capacitor:
Make sure you select a capacitor with the correct voltage and capacitance for your application, with a safety margin for the operating voltage.

Avoid overcharging:
Avoid overloading the capacitor with very high currents or voltages, as this can quickly damage it.

Keep the temperature under control:
Avoid temperatures that are too high or too low, as this can affect the performance and life of the capacitor.

Replace old capacitors:
If you are using old equipment, check the capacitors and replace them if necessary, especially if they are swollen or leaking.

[mix4fix]

However in the 2000s I read two articles by technicians saying that Blackgates were the best at that time.  Nowadays I would trust Miflex if there is plenty of funds.
Check this know graphic from Lampizator for reference:

Wouldn't the result of this competent versus that component depend on what the end user likes in his or her sound? You like it/someone else hates it. You hate it/someone else likes it.

[FullRangeMan]

Wouldn't the result of this competent versus that component depend on what the end user likes in his or her sound? You like it/someone else hates it. You hate it/someone else likes it.

Yes exactly, this valuable chart from Mr.Lukas allows the user to choose the brand according his personal taste and system without spending time and money on purchases and endless subjective tests.
Point to Lampizator 

[wushuliu]

During the past few years, I've talked to a few techs.  Two of these techs use mid grade Nichicon caps.  They say they used to use higher end Blackgates and audio grade Nichicons.  But, they claim audio grade caps and mid grade caps only sound different at first.  Eventually, after some time, they sound the same.  Supposedly, the technology advanced so much that even midgrade caps are now considered higher end?  So, they only use midgrade Nichicons now.  It also lowers their cost as they don't stock as many caps.  And, the reliability are the same too. 

What say you?

The OP seemed to be referring to electrolytics and as such this is a question with no answer - mainly because 'mid-grade' Nichicons are what's easily available now. BlackGates and many other legendary caps (Oscons etc) have been out of production for almost two decades IIRC. So these techs don't really have a choice for more affordable audio-grade electrolytics. It's either Nichicon, Elna Silmic II or $$$$ for Mundorf etc.

[jonbee]

I depends on the application to some degree. My experience is with speakers, mostly film types.
"Cheap, industrial" caps like Bennic and Solen are notably inferior sonically to mid-priced "boutique caps" from Sonicap, Mundorf and ClarityCap, and the improvement doesn't reduce with age, imo. I sometimes have found benefits bypassing mid-level caps with small caps from Sonicap, or for a lot more $, with Audyn True Copper, or Mundorf Silver. At this point, it is more like cooking than engineering, and there is no accounting for taste, nor should there be, imo.