Resolving Hum with Battery Back-up (EcoFlow) vs Power Conditioners: success vs failure

This is an updated post of a post that I asked to be deleted as it became too toxic, and frankly I made mistakes that did not settle down the discussion – but inflamed it - which no one wants.

It is a good topic that generated lots of debate which I summarized in the below to help others with a common sound issue – hum.


This worked for me, but the discussion led me to one conclusion.


The One Certainty of Audio Use Case Testing:

Before I walk through what I tested over 4 months I will reinforce one thing. This is technology use case management – and there is only one certainty:


What works for one, even if it looks like the exact same use case, may not work for another.


This is why this hum is so maddening. I wish that it was as simple “it is a ground loop” or “bad wiring” … “do this” and fix it. So many times the successes of others had ZERO impact on me.

So as you read – take away this. If I reject it, it is not because it did not work for you.

I rejected it, because something in my use case is different than yours, so it did not work for me. For others, they should try it – might work for them.


Which brings me to the trolls (I accuse NO ONE of this - this is a future statement): Please offer an opinion and “what worked for you” but keep your certainty and affiliated condemnation to yourself.  If I rejected it because it did not work for me or chose not to do it - we all have choice.

I solved it for myself and am in marginal gains land but am glad to debate approaches - which is the point of the thread.

There is NO certainty – and anyone who gets high and mighty is displaying audiophile hubris which makes people hate these thread. 

For trolls, please keep your commentary accretive to the discussion – offer new items to debate, suggestions, challenge the premise or testing – and refrain from derogatory comments. Things like “I don’t know why you posted this” or “you are a complainer” or “stubborn for not doing what I say” – keep it to yourself. Debate, question, test – but please lets keep this cordial and not toxic.


I will commit to the same - cordially responding to discussion - debate - suggestions or admit that I did not test that or will not test it (as I resolved it for myself).

That way a reader in this community who has this issue can gain many perspectives.


This inspiration for this post:

I had a hum (very noticeable) on a new system – only on the tube part of a hybrid tube/SS amp - for 4 months that drove me nuts and nothing I read or advice I received helped. I also had an issue with the sub due to power issues (resolved also).

The inspiration to summarize this came from this very well written comment in the OP from @gnaudio - I really hope he reposts it - it was an amazing read and made the point:

Moral of “my” story is many of these companies are small, not large, and make mistakes in their designs and in some cases their poor execution results in massive problems for the uneducated that buy their products based on their claims. I’ve also had some great advice on this and other forums but the “buy the $5k power cable and the $12k power conditioner” are not always the solution but are often touted heavily in these forums. Be careful where you drop large coin in this industry, many of these companies are not run by or have their equipment designed by true engineers. Most are very small companies. For some of us, these downfalls can result in very challenging and unwanted projects.

Reading his journey with his $250K+ system .. it made mine look easy and made me realized the conclusion above.

There is no “right way” to do it. There is no “magic bullet”.

There is only trial and error, and how far are you willing to go to get rid of that damn hum.

My summary – this worked.

My recommendation if you have a hum, or sound issue (and are frustrated) … go to Costco, buy an EcoFlow, and return it with no hassle if it does not solve the issue.

These units start at $1K and scale. Check out CES 2024 … littered with new whole home battery back-up systems – all kinds of different sizes, shapes and price points. CES video summary here:

I bought the EcoFlow Deltra Pro Ultra as it has a new Lithium battery that is safer, lower heat so the fans are silent. Ecoflow Delta Pro has noisy fans as it is old battery tech.


How Did I Find Battery as a Solution to Hum? (Testing is detailed below)

For me, discussions with dealers, bad support from McIntosh, extensive reading and a myriad of testing did not get rid of the hum. Sonus Faber was also unable to resolve their issue with the Gravis VI (1800W amp).

By luck, I landed on this post on battery technology and StromTank .. sine waves and the power of batteries. Specifically, this article:

I was considering it as it was 4 months of pain, had invested an insane amount into my system, but the price for a StromTank is outrageous (I am sure the engineering is amazing but I could not bring myself to do it) which point I came across this older post:

The Audio Impact of Solar Panels and Battery Backup: Comparing Sound Quality of Panels, Batteries, and the Grid

Which .. voila .. solved my issues in one fell swoop.

99.95% no hum.

I will not claim 100%, but it is near perfect and I have entered into the “marginal gains” realm where additional effort does not yield a commensurate benefit.

For me, which I detail below, my journey was:

  • Systems plugged into the wall: Crazy hum via the tubes on the MC451s. Nothing on solid state side (It is a hybrid amp). Loud.
  • Myriad of power conditioners: Hum still there. (Trouble shooting below). Still loud.
  • Different testing (ground loop..etc.): Hum still there. (See below).
  • EcoFlow installed. 99.95% resolution.
  • Niagara 5000 added back in behind the EcoFlow. The .05% does not go away at all.

Solution to 99.95% eliminate hum:

  • EcoFlow Delta Pro Ultra in minimum config – 7.2kW output … 7200 watt output beast up to 21,000 Watts in max config, plugged into 20AMP dedicated line.
  • MC451s (which have the tube hum) plugged direct into EcoFlow, all other units plugged into Niagara 5000 (I own it for now even though it has no value – more on that below).

Use Case:

System: McIntosh end-to-end although tested with NAD M17V2i and M28 amp also (no hum).

The hum came from a pair of brand-new MC451s. These are hybrid 450W amps – 100W tube for midrange and tweeter, 300W solid state for bass. These are bi-amped to Sonus Faber Amati G5s – 4 ohms.

Testing variables included Nordost Blue Heaven (cable and XLR), Tyr 2 (cable and XLR), and final config of Valhalla 2 speaker cables and XLRs. Final power cable is Audience 3m Front Row. Other cables trialed – generic XLRs and speaker cables different AWGs, Front Row audience XLRs and speaker cables, iFi power cables, generic power cables (I have boxes and boxes of cables ready to sell on Audio Mart .. and my useless Niagara 5000).

The amps are attached to MX123 and C12000. The C12000 drives them in stereo mode (attached to a HiFi Rose 150B .. although that is neither here nor there as the “hum” is best heard when nothing is played). It operates in passthru when the MX123 is driving blu-ray, or other appliances (gaming systems, apple TV). There is NO cable (important for groundloop).

Other amps in the system – driving other Sonus Faber Olympica Nova I, II speakers and a 1800W Gravis VI sub. MC257, MC462, MI254 for atmos. All solid state (Zero hum ever).

Power conditioners tested include AudioQuest Niagara 5000, Torus, iFi, TrippLite. Also used UPCs. The only extended testing was with the Niagara 5000 as I bought that one early on .. and the iFi but it is more of a very expensive power bar. Others were bought and returned if the hum did not go away within hours. Also trialed NoHum plugs, plug adapters without the ground, etc.

Testing process to eliminate the hum:

1. The hum is from your systems not being broken in – rejected.

The 2 MC451s and G5 speakers were new. Was told it might go away after they are broken in for 100 hours. I ran them for 100 hours straight while travelling – it did not.

It was not until much later in my testing that I had the “ah-ha” that the solid-state amps and the SS side of the hybrid MC451 did not have a hum (As they are bi-amped).


2. Ground loop – rejected via turning off all breakers but the dedicated 20AMP and disconnecting all non-core electronics.

This is where everything starts and there is a lot posted on ground loops. My conclusion was the only way to really eliminate this was by turning off the entire house (below).

Unfortunately, this is where the McIntosh support started and stopped as they refused to help beyond a generic word document on ground loops. They just finger pointed and told me to get other people to help me. Very disappointing after making such a big investment with them.

I came up with an alternative to “unplug every piece of electronics and then plug them in across the entire house one by one till the hum comes back” approach (which made my head hurt).

I started by turning off all breakers in the house other than to the dedicated 20amp for the sound system. If the hum was gone, I had a ground loop and would have to go through the one-by-one approach. If it was not gone, ground loop was not an issue.

I turned off all breakers, unplugged all non-core systems (Apple TV, HiFi Rose, etc.), as I do not have a cable box that was easy to eliminate, and then ran 3 systems. C12000 and the 2 amps.

Hum was still there.

I then – via a 10AWG/3 industrial shielded extension cord, tested on another 20AMP dedicated line (kitchen – with all appliances disconnected) and other plugs around the house (switching breakers on and off).

Hum was still there.

This approach conclusively eliminated ground loop as an issue.


3. Bad grounding – rejected.

Tested receptacles with Sperry ground and GFCI tester (Went around the residence as I was curious).

Very straight forward – wired properly.

A suggestion was made that a 8’ grounding rod will help.

  • My experience with highly sensitive electronics (non-audio) is that 12’ is the minimum.
  • Maybe. I am not doing this.

Last - Certified electricians were used for wiring. This is a ~2-year-old residence that is high end. This was not a DYI scenario.


4. DC blocking – rejected.

Used the iFi DC blocker to test this. No impact on the hum.


5. You have a serious grounding issue or wiring issue. Your family is at risk of dying in a fiery blaze.

  • No breakers are flipping.
  • I have smoke detectors and CO detectors.
  • I have been in houses where breakers flip. In one I had to swap out for a 200A panel, in another it was knob and tube .. as I renovated a 110-year-old home. This is a well wired home and I have worked with many electricians, having installed multiple pools and as I always have tonnes of electronics in the home.
  • My view is this added safety in the home. By putting the biggest stack of power drawing technology onto the EcoFlow, I have added a great layer of safety. Each Delta Pro Ultra Inverter can be connected with up to five 6 kWh lithium iron phosphate (LFP) batteries to form an inverter and battery stack.LiFePO4 (this is their new tech) are the safest type of lithium battery because they are not prone to overheating and even if they’re punctured, they won’t catch on fire. The cathode material is also non-hazardous and therefore it poses no environmental or negative health hazards.
  • The new battery type is also why it is quieter than the EcoFlow Delta Pro (old battery type).


6. You are just band-aiding, you are not getting to root cause. You have a wiring issue, or grounding issue.


Perhaps. Things I did not do because I am happy with the EcoFlow solution:

  • Replacing what I consider new wiring. See Steve Huff posts – not guaranteed to work.
  • I did not upgrade my wall plugs to gold plated (which might work).
  • Working with the power company as there was one post talking about how a transformer down the street had a bad ground. Possibly, but I do not have the time to do that or the will to even try. Ugh. The power company.
  • Different types of industrial inverters
  • Adding in a grounding rod

BTW, before a troll posts “You are being stubborn for not doing these”, I will remind all that there are no guarantees.

The PURPOSE of this post is to share for others to learn.

I fixed it with the EcoFlow and I am confident that my residence is VERY safe.

Others can try these if they want.


7. Your amp is defective. Replace the tubes - rejected

There are 2 MC451s. Both are new.

I thought of that. I rejected as it is so incredibly unlikely that both are faulty. Plus, they are 133lbs (60KG) each – just the idea of moving them hurts my back.

Last, all the solid states do not have the issue – including the SS side of the MC451.

I believe that my conclusion that this is a tube sensitivity issue is accurate.


8, Buy high end power cables for the amps – rejected.

I am firmly in the camp that power cables make zero difference beyond a certain .. very low .. price. Read across the internet and you will see this battle raging and much engineering support.

I have and tested traditional power cables, heavy duty, iFi Quasars and in the end … bought Audience Front Row cables for all systems ranging in length from 1m to 3m (length made no difference either).

This is where I allowed my own confirmation bias and aesthetic appeal to reign. That is the only reason why I bought them.

It had zero impact. for me.


9. What if the XLR (interconnect) is disconnected from the MC451s to isolate the amp?

The hum is still there. Isolating it to the tubes on the MC451s and sensitivity to the noise in the power – versus the pre-amps.

The hum is not there on the solid-state side.

The fact that these are hybrids and that I have other amps is a real boon to testing theories.

Which brings me to XLRs (interconnects). No impact. I have Nordost Blue Heaven, Tyr2, Valhalla 2, Audience Front Row and a myriad of other interconnects at different price points below the Blue Heaven.

No impact on the hum.

Now on sound? Again, as the war on cables across many forums indicates, this is a highly contested area. My opinion is this:

When I trialed a Blue Heaven versus a Valhalla 2 playing Kashmir by Marcin on SF Amati G5s I heard the difference. Confirmation bias or not, at 1:40 there is this crescendo that feels like it is sucking the sound out of the room.

But did not change the hum.


10. Power Conditioner will improve sound, eliminate hum – rejected (Inconsistent – works for some, snake oil marketing for me).

Frankly, having read far and wide on the issues of power, I am convinced that one person’s success is another person’s snake oil as the variables in solving a problem are so many.

I tried AudioQuest Niagara 5000 (sadly I bought this one), Torus, iFi, NoHum plugs, and nothing removed the hum.

These 2 posts are conclusive evidence for me by Steve Huff – and I believe it reinforces my initial conclusion that there is no silver bullet and what works for some .. does not work for others.

Two years of hell, PS Audio P20 solved it. Rewired the entire house … and that fixed nothing:

Then went a different route with Puritan:

As per the opening, this is a classic technology use case management. In a complex ecosystem of technologies, which leads to near infinite variables, any claim that “something will work” is wrong - the variables are too great.

Which – at the core is why the power conditioner market is so contentious. What works for one, does not work for another.

This is also why their marketing really ticks people off (including me). ALL I WANTED WAS A SOLUTION. I wanted a magic bullet! And for anyone who says, “power conditioners do not claim to fix hum”, oh contraire:

From TrippLite: What benefits can I expect from a Power Conditioner?

  • Protect sensitive electronic equipment from damage or data loss
  • Improve the quality of audio recording or playback by removing line noise that causes "hum"
  • Extend the life of equipment containing electronic circuits,voltage%20fluctuations%20and%20power%20surges.

From AudioQuest Niagara 5000:

The Niagara 5000 features our patented AC ground noise dissipation system, the industry’s widest bandwidth linearized AC filter, and our unique passive / active transient power correction circuitry.

Puritan Master Series: (not tried)

Washing machines, fridges, computers, plug in power supplies, low energy lighting, dimmer switches, heating pumps, thermostats, solar power installations, the list of culprits directly injecting rubbish into our mains supply is endless. Effectively anything connected to the mains in your house and all of your neighbours houses contributes to the problem. And that is before you consider more distant heavy industrial machinery, and it doesn’t stop there…..

Rebalances the AC sine wave, removing all DC components, this enables transformers to work efficiently and quietly, realising their full dynamics and power range .. Star earthing plan eliminates ground loop hum, reduces the noise floor, improves definition … Multiple, cumulative, sympathetically tuned stages of purification (39 independent elements) substantially remove all interference types …. Cleansed earth removes noise from the earth line further enhancing clarity and dynamics


I then started to read engineering reviews like this one on the Niagara 1200 which concluded:

If you want to spend $1000 on a sturdy box with surge protection, go ahead. But please don’t assume it does something for your sound. It does not.

Or PS Audio power conditioning:

In my opinion, it is a waste of technical talent to be building such products. I see no reason to recommend PS Audio Stellar PowerPlant 3.


Steve Huff – PS Audio P20 regeneration and Puritan worked for him.

I come back to my opening conclusion – what works for one, might not work for another. There are no silver bullets.

The only thing that worked for me was the EcoFlow and with beefy 7200W minimum output, it can handle a lot of load which brings me to a tangential issue that I also solved.


Sonus Faber 1800W Gravis VI side bar:

Of interest, the one issue my Niagara 5000 did solve was a product defect in the Sonus Faber Gravis VI. It is a 1800W sub - and occasionally it went "insane". (I have the videos .. they had never seen this before).

It would just go nuts (loudly). When this happened, pulling the XLR would not stop it - it was an internal "go nuts" and the only way to stop it was to unplug it.

They had no idea what was going on and in fact replaced it (which was a huge pain as the thing is massive) - and it kept happening. I concluded that if it did not get a full draw when it needed it at peak - that it would go nuts. I told them this – they did not even try to test it which I was disappointed by. Use case testing is what they should do!

The Niagara 5000 has a power well with a 90A reserve. While I was doing the whole hum thing, I theorized that the reserve would solve this. It did.


When I direct plugged the sub into the EcoFlow it also solved this problem as it is a beast serving up power – 7.2kW (7200 watt) minimum. I was able to replicate the issue with certain scenes in Blu-Rays.

So I just have to get around to unplugging and selling the Niagara as the EcoFlow serves as a surge protector … essentially making it useless in my config.


Caveat: StromTank.

I bet that works. It is a fancy battery .. built for audio. I bet it is awesome.

But I am not paying that price. Sorry.

In the meantime, my EcoFlow works great and the solar/battery industry (As seen at CES) is expanding massively making the audio market look like a speck of sand in comparison. This area will only get better and better.


11. But how good is the EcoFlow inverter?

EcoFlow sounds great to me. As I said, it is now 99.95%.

If a better inverter were put in front of the battery, would it be better? No idea. That is the essence of the StromTank .. audio quality components.

The Niagara 5000 in-front of the EcoFlow did not get me to 100%. At times I can hear a little niggle hum. But close enough for me.


12. I thought that power conditioners should never be used on amps as they ruin sound?

That seems to be the consensus.

The one piece of interesting advice from McIntosh was that in their reference system (which has a tonne of amps), everything is plugged right into the wall. I had several people say that too me.

This is the fundamental advice from many – rewire your dedicated line. But as the Steve Huff experience proves, that is not guaranteed either. He did it and still had the problem as it could be the power coming into the house. He also went over to his mom’s house and the noise disappeared.

In my opinion, plugging it into the EcoFlow allows me to do what McIntosh recommended. It is just like plugging it into the wall (and if I pull the 20AMP cord out of the EcoFlow, it is running on pure battery for testing).




There is no silver bullet.

Power issues are a nightmare.

If you have sound issues, here is a long list of things to try including an EcoFlow (or other solar battery system).

The best thing about the EcoFlow? If it does not work … return it to Costco.


It worked for me.





I think you can switch between battery power and grid with the app on your phone. You can also have it on a schedule to automatically switch back and forth at set times. I will follow up once I hook mine up in a few weeks. Great discussion thank you

Anyone who understands and respects what research is should generally not request a thread be eliminated for sake of regretting his/her own comments within it, once other posters have made significant contributions of their time and knowledge.
That’s less my opinion and more just how disciplined researchers expect exchange of info to happen. The fly-by-the-night nature of some internet forum threads might see “research” thrown around by users who don’t actually have much regard for what that word requires. It can be unfortunate.

@benanders  The only "regrettable" statement is that I provided an opinion on a vendors employee - which several people then mentioned by name and pointed out positives. Therefore, I asked the moderator to remove it as it was wrong (of me) to mention that person.  I should not have done that.

The moderator - as that is their job - made the decision to remove it.

Everything else - I stand by my testing, my statements and was more than capable of taking on those who trolled versus adding value to the discussion.

Couldn't the underlying problem eventually cause the solution to fail?

@jji666  not sure how. Per the OP this is causing the hum on the tube half of a hybrid MC451 - nothing on any other components.

Furthermore, per the OP and to dispel a number of comments like that:

1. Ground is tested fine (See OP)

2. No ground loop (per OP)

3. DC blocking did nothing (Per OP)

This is a single component resolution.

I think you can switch between battery power and grid with the app on your phone. You can also have it on a schedule to automatically switch back and forth at set times. I will follow up once I hook mine up in a few weeks. Great discussion thank you

@dolfan  .. the app is great. You absolutely can create custom power settings like when to charge, etc. Share when you set it up to compare.