Without knowing what you're doing, it is hard to tell you how to improve it.
Discounting SEO strategy and PPC because of low search volumes is kind of throwing the baby out with the bathwater, likely, *someone* is searching for your services (otherwise, perhaps it is time to consider a new service).

If the market is enough to justify your entire business plan, there is enough to justify a targeted marketing plan.

I'm happy to discuss the details and learn more of what you have done, and are doing now, to attract traffic - then offer suggestions on how to improve.

All the best,
-Shaun

I'm consulting with local client with a similar issue. We did some SEO & PPC as well with minimal results.

They have a physical product so we created a trade show schedule and leads started flowing with increase of over 50% in the last 6 months.

We also set up a road tour of clients/non-clients in our local area which yielded new contacts and leads. In addition, we are using a similar approach on Linkedin with groups as well as video ads.

The other opportunity that we have focused on is a referral program with current clients. We created a very specific and strategic outreach program via emails, calls & visits that is starting to yield leads and sales.

Do you have a physical or digital product or service?

I see this question has been out here unanswered for a couple months. It's a tough one to answer so I'm not surprised. While not knowing your business or niche well, here are a couple thoughts. Perhaps you've pursued these ideas already, but I thought I'd toss them out.

You mentioned PPC wasn't effective. Was that only Google and/or Bing PPC? If you haven't tried targeting that space via Facebook Ads, that might be worth a try. The targeting is excellent and the clicks are still affordable. LinkedIn Ads have less targeting options and are more expensive but depending on the niche, it could be an option - especially in B2B. There are some creative ways to broaden the audiences on these mediums by highlighting conferences, trade mags, and industry websites as interests of the audience.

Do you have a list of targeted accounts in the niche? Account Based Marketing (ABM) is great way to micro target your ideal customer profile. It's not easy but can help you build awareness at the very least.

Are there some influencers or known experts in the space you could reach out to directly with your content? Have someone else in the space share your content with their following could help you reach more people.

I know directly contacting someone on LinkedIn can be intrusive but if you're approaching with content they'd find valuable, the outreach could be well-received. Linking out to experts via a blog post or Twitter post can also get attention.

Engaging influencers on LinkedIn and Twitter by first sharing their content can put you on their radar making the outreach a little warmer when you do directly contact them.

Are there smaller conferences or meet-ups in the niche you could sponsor or attend as a sponsor? Oftentimes, you'll get the attendee list as a sponsor and can follow-up with an email campaign. If the email campaign was in the form of a drip campaign, you could warm them up with your content and then follow-up with a compelling offer.

With all of these above, make sure that your remarketing tags are set on your site. If you do get the traffic, make sure they're seeing you again after they leave on Facebook, LinkedIn, and other niche sites via Google PPC.

Hope that offers a couple ideas. Happy to brainstorm further if you'd like.

Lead generation and ppc strategies should work, even for a B2B. You have people in Business, and they are decision makers, so they still use devices as people. It’s a matter of identifying the correct people.
On the other vertical I would concentrate in other tools, specially designed for business (depending on geographic area and industry).
I could guide you for your specific needs through a call.
Best,
Ana